06 no7 theory

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No.7 Common Channel Signaling

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1 The relationship between signalingnetwork and telecom network

Overview

2 The development of No.7 signalingsystem

3 The development goal of No.7

signaling system

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No.7 are common channel signaling systems .

The No.7 signaling system (abbreviated as SS7) was first stipulated by

the CCITT in 1980 (in the orange cover book), and was twice

modified and supplemented in 1984 (blue book) and in 1988 (white

book). The general goal of the No.7 signaling system is to suggest an

internationally standardized common channel signaling system with

general applications fields so that the digital communication networks

with digital SPC switches can work in the best status. Furthermore,

such networks can provide sequential and highly reliable transmission

with no loss and no repetition.

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You will study

1 Basic conception

1 Basic conception

2NO.7 signaling system

2NO.7 signaling system

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signalingsignaling

It is the dialog language for the communication

between various parts of the telecom network. It ensures the

network to operate normally as an integer.

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Classification of signaling

Subscriber signaling:between sub. and switch:between sub. and switch

Inter-office control the setup and release of callWorking areaWorking area

Monitoring signals: monitor the changes of: monitor the changes of

call states or conditions in the linescall states or conditions in the lines

Selection signals in routingin routing

Operation signals management andmanagement and

maintenance of telecom networksmaintenance of telecom networks

SignalingSignalingfunctionfunction

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Common channel signalingCommon channel signaling

Channel associated signalingChannel associated signaling

TransmissioTransmissio

n pathn path

Line signalingmonitors the states of inter-office

calls

Register signaling also selection signals and network

management signals

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Opposite end alarming

code for out of frame

16 frames,125 s !16=2ms

F0F15

0 1 15 16 17 30 31

32 slots ,256bit,125s, 1frame

Reserved for

international

(presently 1)

Synchronization

time slot

Voice channel time slot

TS1-TS15

Voice channel time slot

TS17-TS31

Frame synchronous code

D1 D2 D3 D4 D5 D6 D7 D8Even

frame

Odd

frame

F1 a b c d a b c d

Signaling code for

voice channel 16

Signaling code

for voice

channel 1

1 1 A1 1 1 1 1 1

Reserved for

international

(presently 1)

a b c d a b c d

Signaling code

for voice

channel 15

Signaling code for

voice channel 30

Synchronization:A1=0; A2=0

Out of sync:A1=1; A2=1

Figure 1.3.4-1 PCM 30/32 frame format

1 0 0 1 1 0 1 1 0 0 0 0 1 A2 1 1

Multi-framesynchronous

code

Multi-frame alarmand reserved bit

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v+s

s

v

s

v

LineLineterminalterminal

ExchangeA

ExchangeA

Register

Register

ExchangeB

ExchangeB

v+s

ISDNISDNlineline

terminalterminal

LineLineterminalterminal

ISDNISDNlineline

terminalterminal

Register

Register

SignalingSignaling

terminalterminal

S

v

vvv

SignalingSignaling

terminalterminal

Common Channel Signaling System

p54

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ExchangeA

RegisterRegister

Exchan

geB

Lineter

minal

Lineter

minal

v+sv+s

v+s

v+sv+s

v+s

Subscriber Line Signaling

associated channel signaling

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4.3.1 Overview

1. Advantages of Common channel signalingCompared with associated channel signaling, common channel

signaling has many important advantages:

1) Information can be switched between processors much faster

than in channel-associated signaling.2)With a huge signal capacity, it can hold dozens or even hundreds

of different kinds of signals, thus providing more new services.

3)With a great flexibility, it can provide more new services simply

by modifying software to increase signals.4)Line signaling device is not needed any more at any trunk station,

which shall greatly reduce investment costs.

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Um

MSC/VLRMSC/VLR

HLR/AUCHLR/AUC MSC/VLRMSC/VLR

SMCSMC

MAP

C

DMAP

MAP

E

PLMNPSTN

ISDN

PSPDN

TUP ISUP

OMC S Network Management Center Q3

TCP/IP X. 25

BSC

BTS

BTS

BSSAP

A

Abis

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5) Since line signaling is no longer needed, trunk devices can beused both in calls from A to B, and in calls from B to A.

In such bi-directional working modes, even less circuits arerequired than when trunk circuits are respectively used in single calldirections.6) When a call is being set up, signals related to this call can be sent.In this way, the subscribercan change the already setup connections.For example, the subscriber can transfer one call to another place, or

request a third party to join the present connections.7) Signals can be switched between processors so as to be used formaintenance or network management.8) The No.7 line signaling can provide powerful support for ISDN,IN, TMN and cellular mobile communication systems, as this

signaling is their basis.9) The signaling system is not restricted by the voice channelsystem, thus making it very flexible to add and change signal types.

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Disadvantage A contradictory phenomenon

1)The error rate of the common channel signaling system must be

very low.

2) Its reliability must be much higherthan the channel associated

signaling system. This is because once the data link fails, all related

calls between the two related switches shall be affected.

3 bi-directional trunk working modes existconflict of seizure.

4) The SS7 systems that every transnationalcorporation produces are having some problems

in compatibleness.

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Signaling systemSignaling system

signaling system includes a set of integrated signaling

and operation procedure.

Signaling system is the collection of software and

hardware which generate transmit receive and

recognize the signaling.

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NO.7 signalingNO.7 signaling

protocol systemprotocol system

structurestructure1 System structure and the

function of every layer

2Message structure

2 The introduction of signaling system

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2a The earliest structure of No.7 signaling protocol

system

2a The earliest structure of No.7 signaling protocol

system

SCCPMTP3 network layer

MTP2 Data link layer

MTP1 Physical layer

TUPISUP DUP User part

Message

transfer part

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4 The structure of No.7 signaling protocol system

OSI model

MTP1MTP2MTP3

MAP

TCAP

TCAP

Intermediate

service part

ISP

SCCP

OMAP

TCAP

CCITT No.7 Signaling functional class

TUP DUP

ISUP

Transport layer,

session layer and

presentation

layer

Applicationlayer

Physical

layer, datalink layer andnetwork layer

Figure 4.3.1-1 The relationship between No.7 signaling and OSI model

OSI 1,2,3

OSI 4,5,6

OSI 7

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User part

Signal network

function

Signaling link

function

Signaling data

link function

L4

L3

L2

L1Physical path

Logical path

Logical path

Logical path

User part

Signal network

function

Signaling link

function

Signaling data

link function

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For example, the President of a Chinese company is

communicating with the President of a Pakistan company ,

however neither speaks the others language. Each employs an

English translator and the translated messages are sent by the Faxoperator over physical communication channel. Thus, the two

presidents are communicating with each other through five layers

below them.

Give an example

Eff i

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Company A

(in China)

physical communication channel

Company B

(in Pakistan)

Chinese President

Translator

Fax Operator

Write to paper

Print to paper

President

Translator

Fax Operator

Write to paper

Print to paper

Effective

Communications

telegraph

talk

English

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(1) Use structure of function level. Between

function levels they have relation and also

independent. The change of certain level willnot change another level.

(2) Use the special interface between function

levels to communicate with each other.(3) For two signaling systems, L1 is the only

physical path. All the signaling messages are

sent through L1. At same time ,L2 L3 L4only process the message sent by same function

level of the another system.

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4.3.2 Common channel signaling network

Since in common channel signaling systems, the signalingsignals and voice signals are separately transmitted, so a

dedicated common channel signaling network can be composed.

Base of CCSN is Data Communication Network.The common-channel signaling network consists of the

following parts.

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The common-channel signaling network consists of the following

parts.

1)Signaling point (SP)

It refers to the node in the signaling system that provides commonchannel signaling. SP can also be divided into source points (the SP

that generate signaling messages)OPC(Originating points code) and

destination points (i.e.,the SP that receives signaling

messages)DPC(destination point code). Actually, SP is part of aswitching system.

2)Signaling transfer point (STP)

It refers to SP that transfer signaling messages from one signaling link

to another. They are neither source points, nor destination points. That

is, they are the middle node points during signaling transfer.

OPC or DPC is 14-bit address for CCITT (24-bit for China)

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B

Voice channels

A

Signaling link

C

SP ASP B

STP

2_2_2 3_3_3

8_8_5

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OPC or DPC is not absolute. OPC and DPC are relative, the OPC of

certain Office, for other Offices, is DPC.

for example, the SP of switch A is 2_2_2, and SP of switch B is

3_3_3. If you work in switch A then 2_2_2 is OPC for A, and 3_3_3

is DSP for A. If other work in switch B, then 3_3_3 is OPC for B, and

2_2_2 is DPC for B.

B

Voice channels

A

Signaling link

C

2_2_2 3_3_3

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switches A

OPC is 2_2_2

DPC is 3_3_3

switches B

OPC is 3_3_3

DPC is 2_2_2

B

Voice channels

A

Signaling link

C

2_2_2 3_3_3

3)Signaling link( N7 SLK)

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3)Signaling link( N7_SLK)It refers to the signaling message channel that connects an SP andanother SP( or STP).

Signaling link set( N7_SLS)

A bunch of signaling links directly connecting two SP (includingSTP) form one signaling link set.

ROUTE ( N7_ROUTE)One such set usually includes all parallel signaling links.

ROUTE SET ( N7_RS)It is also possible to set several routes between two SP.

LINK

LINK SETROUTE

ROUTE SET

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LinkLink Set 1

Link Set 2

ROUTE1

ROUTE2

ROUTE3

ROUTE SET

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the signaling mode

1)The associated mode

In this mode, messages related to the voice channel connecting

two switches are sent on the signaling link that directly connects

two switches, as shown in the Figure.

B

Voice channels

ASignaling link

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2)Non-associated mode

This is as shown in Figure 4.3.2-1 (b). Signaling messages between A

and B are transferred by several signaling links according to the

current network status, but the voice circuit is the direct route betweenA and B. In other cases, the common channel signaling messages are

transferred on different paths.

B

Voice channels

A

Signaling link

This mode is normally not used, as it is rather difficult to exactly

identify a route at any given time.

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3)The quasi-associated mode (Figure 4.3.2-1(c)

This can be called a special case of the non-associated mode. In this mode,

signaling messages between switches A and B go through the severalpreset concatenated signaling links, but voice signalsgo through the direct

channels between A and B. Normally, different transmission carriers are

used in the common channel signaling systems and their related voice

links.

B

Voice channels

A

Signaling link

CSTP

SP SP

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Now, modern telecommunications networks include:

1. Telecommunications basic network;

2. Signal supports network;

3. Digital clock synchronization network;

4. telecommunications manage network;

p5

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B2

A2

A1

LSTP

HSTP

HSTPHSTP

D DD

DDD

DD

B1

C1

C2

A B

C

A

C

B

B

BB

B

SP

SP

SP

SP

A

A A

A

A

C

B

HSTP-LSTP: DLINK

LSTP :CLINK LSTP :BLINKSP-LSTP ||:ALINK

The 3-level signaling network

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1) Functions of the signaling data link level(1st level)

The 1st level defines the physical, electrical, and

functional features of the signaling data link, and is

thus similar to the OSI physical layer. It determines the connection method with the data

link, and provides an information carrierfor the

signaling link. In digital transmission, signaling

data links are usually digital channels at 64kbit/s.

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2) Functions of the signaling link level

(the second -level) The second level defines the signaling

message transmission functions andprocedure related to its transfer on asignaling data link.

The second level and the first signalingdata link used as a whole as an information

carrier, provide a signaling link betweentwo signaling points for the reliable transferof messages.

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signal unit demarcation and localization

error check 16 bit check code

error correction FSN;BSN;FIB;BIB; basic error correction and

preventive cyclic retransmission(PCR)

initial localization when recovering links after the firststarting and the link is failed

error monitoring of signaling link prevent the overmuch

retransmission when error occurs

flow control prevent the link congestion if the load on the link

is too heavy

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3) The signaling network function level

(the third level)

Within a signaling network, each switching

node is allocated a signaling point code,which is 14-bit address (24-bit for China).

Every CCITT No.7 message then contains

the point code of the originating node

(OPC) and the destination point code

or( DPC).

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message routing selecting the signaling link that is used by each

signaling message to be transmitted

message distribution send the message to a user part or level-

3functions after receiving the message

message authentication to determine whether a signaling point is

the destination point of a message after the signaling point receives the

message.

signaling service management control message routing

etc.signaling link management control the locally connected

link

groupsignaling route

management

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Messageidentification

Messagechanneling:

Messagedistribution:

Come from the second levelGo to the fourth level

Go to the second lever

Come from the fourth level SLS and DPC

DPC and SI

LINK BY LINK

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4) The user part (the fourth level)

The user part is the fourth function level of

the NO.7 signaling system. Its main

function is to control the setup and releaseof various basic calls.

The major user parts include the telephone

user part (TUP), the ISDN user part (ISUP)and the signaling connection control part

(SCCP).

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transmission system DTDT

2048kb/s

Level 1

Signaling link

Level 2

MPMP

Level 3

Message transfer part

Level 4

STBSTB

semi-permanent connecting

64kb/s

NET NET

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The signaling messages structure of TUP

The NO.7 signaling are sent in unequal message units. And the MTP

mainly controls the message transfer. The three signal units of the CCITTstipulated NO.7 signaling include the message signal unit (MSU), the link

status signal unit (LSSU) and the filling-in signal unit (FISU). Their

formats are as shown in Figure 4.4.2-1.

MSU

LSSU

FISULI

0

The first transmitted bit

F LI FIB FSN BIB BSN FCK

LI

1~2

Note: SF---- Status Field The first transmitted bit

F CK SF LI FIB FSN BIB BSN F

LI>2The first transmitted bit

F CK SIF SIO LI FIB FSN BIB BSN F

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The main meanings of 3 signal units:

The fill-in signal unit (FISU)

Just as its name implies, when no other signaling units need to be senton the signal link, the FISU shall be sent.

It is used to give positive or negative acknowledgement

to the received MSU,

to show whether the local signal link is working normally,to detect the error rates of the remote signaling link.

FISU is used to keep the synchronization of signal links, so it is also

called the synchronization signal unit.



LI

0Generate by MTP2

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The link status signaling unit (LSSU)

At the initialization of the signal link, to control the flow of

MSU,and the link failure status, LSSU is continuously sent from one

end to the other reciprocally, to show the adjustment status information

of each other.

The format of the SF field in LSSU is as shown in Table 4.4.2-1.

LSSULI

1~2

Note: SF---- Status Field The first transmitted bit


Generate by MTP2

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Ta b le 4 .4 . 2 - 1 C o d e a n d m e a n i n g o f t h e S F f ie l d

H G F E D C B A sta tu s m e a n in g

0 0 0 sta tu s 0 T h e l i n k i s o u t o f o r d e r.

0 0 1 sta tu s N T h e l i n k i s a t n o r m a l a d j u s t in g s ta t u s .

re se rv e d 0 1 0 sta tu s E T h e l in k i s a t e m e r g e n t a d j u s ti n g s t a t u s .

0 1 1 sta tu s O S T h e l i n k f a i l s, se r v i c e s i n te r r u p t

1 0 0 sta tu s P O T h e P r o c e s s o r o r u p l a y e r m o d u l e f a i ls . , ,se r v i

1 0 1 sta tu s B T h e l i n k i s b u s y.

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The message signaling unit (MSU)

The message signaling unit(MSU) is related to user part, and used

to send the user part messages. The length of MSU is variable, with

a maximum length of 272 bytes.

MSULI>2 The first transmitted bit


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The meanings of the various fields are as follows:

1) Flag (F):the starting flag indicates the start of a signal unit. The start

flag of a signal unit is usually the ending flag of the preceding signal

unit. The ending flag indicates the end of a signal unit, and has a flag

code type of01111110.

F F F F F

signal unitssignal unitssignal unitssignal units

01111110

start

start end

delimitation

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F F F01111110

01111110 01111110

F F F010111110

In order to ensure that 01111110 code do not appear in other parts

of the unit, after fifth 1 (with more than 6 continuous 1s) we

appended a 0 in outgoing end, and remove it in receive end.

desequencing code

F

??

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2) Length indication code (LI): the length indication code indicates the

quantity of octets located after the length indication code and before the

check bits, is a number within 0 63 represented by a binary. The

length indication codes of 3 forms of signal units are respectively:

octets byte 1 byte = 8 bit

LI 0 byte: filling-in signal unit (FISU)

LI 1 byte or 2: link status signal unit (LSSU)

LI>2 byte: message signal unit (MSU)

In message signal unit, when the signaling information field has

tets more than 62, LI =63.

3) The status field (SF): if the length indication code is 1, (LI=1)then the

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Standby

5

Status

indication3

C B A


status field is one octet; if the length indication code is 2, then the status

field is two octets. The code of the link status indicator is shown in Table

4.4.2-1.

HGFED C B A status meaning

0 0 0 status 0 The link is out of order.

0 0 1 status N The link is at normal adjusting status.

reserved 0 1 0 status E The link is at emergent adjusting status.

0 1 1 s t a t u s O S The link fails, services interrupt

1 0 0 s t a t u s P OThe Processor or up layer modulefails. , ,services interrupt

1 0 1 status B The link is busy.

1

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4) Sequence number (FSN, BSN):

the forward sequence number (FSN) is the No. of the signal unit

itself.

the backward sequence number (BSN) is the No. of theacknowledged signal unit.

Both forward sequence number and backward sequence number are

binary numbers with a length of 7 bits, in the cycling sequence from0 to 127.



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5) The indication bits (FIB, BIB): together with FSN and BSN, the

forward indication bit (FIB) and the backward indication bit (BIB)

are used forbasic error control, with a length of 1 bit, so as to

perform the signal unit sequence number control and

acknowledgment.

6) The check code (CK): each signal unit has the 16-bit check

code for error detection.

7) The service information octet (SIO): in the message signal unit, the

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service information octet includes the Service Indication Code and sub-

service field. The structure of the service information octet is shown in

Figure 4.4.2-2.

Figure 4.4.2-2 SIO formatThe service indication codes used in the international signaling network

are as follows:

DCBA

Sub-service

field

Serviceindication

code

DCBAThe first transmitted bit


8 16 8n(n2) 8 2 6 1 7 1 7 8

SSF SI

Bit: DCBA(SI)

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0000 signaling network management message

0001 signaling network test and maintenance message

0010 reserved

0011 SCCP0100 the telephone user part (TUP)

0101 the ISDN user part (ISUP)

0110 the data user part (messages related to call and circuit)

0111 the DUT (performance registration and canceling message)

1000 reserved for MTP to test the user part

1001

1010

1011

1100 reserved1101

1110

1111

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The sub-service field (SSF) includes the indication code (bits C and D)

and two reserved bits (bits A and B). The network indication codes are

distributed as follows:

bit:

DC

00 international network

01 reserved (for international use only)

10 domestic network

11 reserved for domestic use

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8) The signaling information field (SIF): the signaling information

field consists of an integral number of [2, 272] octets. The format and

code of the signaling information field is stipulated in detail in each

user part. The signaling information of the TUP user part shall be

illustrated with examples in the following sections.

4 5The Telephone User Part (TUP)

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4.5The Telephone User Part (TUP)

In the No.7 signaling system, all phone signals shall be sent throughthe message signal unit. In the phone message signal unit, only thesignal information field (SIF) is related with the phone control signal ofthe telephone user part, and handled by thetelephone user part.

The signaling program of the TUP is similar to the channelassociated signaling, except that the signal content is much more thanchannel associated signaling, the representation of signaling

information and transfer is also different. Besides, ordinary phoneconnections, it can also provide a part of subscribers withsupplementary services, such as calling back busy, call transfer, andmalicious call tracing.

The length of the signal information field (SIF) is variable, and is

related to the phone call control signals of the telephone user part. Itnormally consists of three parts: the label, the head code and signalinginformation.

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F FCK SIF SIO LI FIB FSN BIB BSN


8 16 8n 8 2 6 1 7 1 7 8n>2

Signalingmessage

labelH1 H0

DPCCIC OPC

4 12 24 24

8n 4 4 64

Format of TUP message units

in national networks

4 5 1 The label of phone signaling message

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4.5.1 The label of phone signaling message

Each signaling message is a set of information used separately by

the different No.7 signaling user part. To label the original and

destination point of each signaling message, in each signalingmessage unit there is the messages channeling label with a fixed

length.

The label of telephone signaling messages is as shown in Figure 4.5.1-

1. It includes three fields: the destination signaling point code (DPC),

the originating signaling point code (OPC), and the circuit

identification code (CIC).

CIC OPC DPC

The first transmitted bit4 12 14/24 14/24

Figure 4.5.1-1 Flag in the signaling message

2) The circuit identification code CIC

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2) The circuit identification code CICThe circuit identification code is distributed to each phone circuit, by

bilateral agreement or preset principles:

(1) The 2048kb/s digital channelFor the 2048kb/s digital channel, the 5 lowest bits in the 12-bit CIC is

the time slot code of the voice channel.

the other7 bits represent the codes of the PCM systems between DPC

and OPC.

Primary group (E1) consists of 32 time slots, 25=32so that 5 bits are enough.

27=128

128*32=4096 voice channels

one 64kb/s No 7 link is able to service for 4096 trunks.

7 bits 5 bits

32 TS

128 E1

(2) The 8448Kb/s digital channel

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(2) The 8448Kb/s digital channelFor the 8448Kb/s digital channel, the 7 lowest bits in the 12-bit CIC is

the time slot code of the voice channel, and the other 5 bits represent

the codes of the PCM systems between DPC and OPC.Second order group consists of 4 Primary group 32*4=128

27=128

7 lowest bits for E2 are enough.

5 bits 7 bits

128 TS

32 E2

27=128 and25=32

128*32=4096 voice channels

one 64kb/s No 7 link is able to service for 4096 trunks.

4.5.2 Title code distribution

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LEAD CODES

SI H1 H0 LABEL

8n 4 4 64

CIC OPC D PC

4 12 14 14


8 16 8n(n2) 8 2 6 1 7 1 7 8 The first transmitted bit

SSI SI

All phone signaling messages contain a title that consists of thehead code H0 and H1.

H0 marks the message group, and H1 contains one message code,

or, marks the format of these messages in case of complex messages.

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Table 4.5.2-1 Distribution of the head codes in the TUP messages

messagegroup

H1

H00000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111

0000 Reserved for dom esticFAM 0001 IAM IAI SAM SAO

FSM 0010 GSM COT CCF

BSM 0011 GRQ

SBM 0100 ACM CHG

UBM 0101 SEC CGC NNC ADI CFL SSB UNN LOS SST ACB DPN MPR EUM

CSM 0110 ANU ANC ANN CBK CLF RAN FOT CCL

CCM 0111 RLG BLO BLA UBLU BA CCR RSC

GRM 10 00 M G B M B A M G UM U AH GB H BA H GU H UA G RS G RA S GB S BA S GU S U A

1001 reservedCNM 1010 ACC

1011

Reserved for international anddomestic

NSB 1100 MPMNCB 1101 OPR

NUB 1110 SLB STB

NAM 1111 MAL

Reserved for dom estic

4 5 3 M i f i l i TUP

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4.5.3 Meanings of signal messages in TUP

1) The forward address message (FAM)

(1) The initial address message (IAM)

CIC OPC D PC

SI H1 H0 LABEL

0001 0001

Address Address Number Signaling Flag R e s e r v e dcaller type

LKJHGFEDCBA FEDCBA

F A M 0 0 0 1 I A M I A I S A MS A O

H1 0001 0010 0011 0100H0 0001

IA

MSignal

information

Bit 8n 4 12 2 6 4 4LKJIHGFEDCBA FEDCBA 0001 0001

The number

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Address digital(in binary)

of address

digital (in

binary)

Signaling flagNot in

useCaller type H1 H0

0000-1001: standfor numbers 0-9

1010, 1101, 1110:reserved

1011, 1100: used inthe internationalcall connection

ST: = 1111(end of the address)

0000: filling code(to guarantee thelength of the

variable field lengthis integral multipleof 8bit. )

BA: address character00 local call subscriber number01 reserved10 domestic valid number11 international number

DC: circuit character00 connection without satellite circuit01 connection with satellite circuit10 reserved11 reservedFE: continuity test00 need not continuity test01 continuity test isrequired in this section10 continuity test isdemanded in the previous

section11 reservedG: phone echo canceller0 excluding phone echo canceller

1 including phone echo canceller

H: international incoming call0 not international incoming call1 international incoming callI: changing into issuing a call0 not changing into issuing a call

1 changing into issuing a call

J: complete digital channel

is demanded.0 normal call1 complete digital channelis demandedK: signal communicationschannel0 any channel1 all No.7 signalingchannels are demandedL: reserved

FEDCBA000001 operator, French000010 operator, English000011 operator, German000100 operator, Russian

000101 operator, Spanish000110 language negotiated by both sides

(Chinese)

000111 language negotiated by both sides

001000 language negotiated by both sides

(Japanese)001001 domestic operator (with the function

of interpolation )001010 ordinary subscriber, used in the

toll(international)-toll and toll(international)-

local offices.

001011 priority subscriber, used in thetoll(international)-toll and toll(international)-

local offices.

001100 data call001101 test call001110-001111 reserved010000 common, billing free010001 common, regular001010 common, subscriber table,immediate010011 common, printer, immediate010100 priority, billing free

010101 priority, regular010110-010111 reserved011000 common, used in the local-local offices.011001-111111 reserved

Figure 4.5.4-1 IAM format

p341

(2) The initial address information (IAI) with additional information

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(2) The initial address information (IAI) with additional information

For a call between local and toll switches, or for a special service call,

additional information such as the caller number is required, thus the

initial address message (IAI ) with additional information is used.CIC OPC D PC

HGFEDCBA LK BA

first presentation Adress Number of address Signaling flag

FEDCBA 0010 0001

Reserved Calling user type H1 H0 Flag

2 6 4 4

Billing

informati

on

Original

callee

address

Caller

line

label

Additional

route

information

Additional

caller

information

Close user

group

information

Network capability or user

performance information

(optional)

8n 8 8n 8n 8n 40 8

p342

Bit 8n 4 12 2 6 4 4LKJIHGFEDCBA FEDCBA 0001 0001

The number

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Address digital(in binary)

of address

digital (in

binary)

Signaling flagNot in

useCaller type H1 H0

0000-1001: standfor numbers 0-9

1010, 1101, 1110:

reserved

1011, 1100: used inthe internationalcall connection

ST: = 1111(end of the address)

0000: filling code(to guarantee the

length of thevariable field lengthis integral multipleof 8bit. )

BA: address character00 local call subscriber number01 reserved10 domestic valid number

11 international numberDC: circuit character00 connection without satellite circuit01 connection with satellite circuit10 reserved11 reservedFE: continuity test00 need not continuitytest01 continuity test isrequired in this section10 continuity test is

demanded in the previoussection11 reservedG: phone echo canceller0 excluding phone echo canceller

1 including phone echo canceller

H: international incoming call0 not international incoming call1 international incoming callI: changing into issuing acall0 not changing into issuing acall

1 changing into issuing a call

J: complete digital channelis demanded.0 normal call1 complete digital channelis demandedK: signal communicationschannel0 any channel1 all No.7 signaling

channels are demandedL: reserved

FEDCBA000001 operator, French000010 operator, English000011 operator, German

000100 operator, Russian000101 operator, Spanish000110 language negotiated by both sides(Chinese)000111 language negotiated by both sides001000 language negotiated by both sides(Japanese)001001 domestic operator (with the functionof interpolation )001010 ordinary subscriber, used in thetoll(international)-toll and toll(international)-

local offices.001011 priority subscriber, used in thetoll(international)-toll and toll(international)-local offices.

001100 data call001101 test call001110-001111 reserved010000 common, billing free010001 common, regular001010 common, subscriber table,immediate010011 common, printer, immediate010100 priority, billing free010101 priority, regular010110-010111 reserved011000 common, used in the local-local offices.011001-111111 reserved

-

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(3) The subsequent address message (SAM) with multiple addresses

After sending the IAM message in the OVERLAP mode, if the least

sent code bits (except the number bits sent in the IAM message) isgreater than 1, then the subsequent address message (SAM ) with

multiple caller address figure shall be used.

(4) The subsequent address message (SAO) with one address figure

After sending the initial address message, all the remaining calleesubscriber numbers can be sent in SAO.

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Local exchange Local exchangeTandem exchange

IAM

SAM

SAO IAM

ACM

Ringing

ANCANCCLF CLFTalking

RLGRLG

CBKCBK Callee

release first CLFCLF

RLG RLG

Si li t i i th ZXJ10 it h N 7 i li t

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No.: 000061 sequence number: 6403 code: SHOW_SIGNAL_TRACEdate: Dec.10, 1997 time: 14h 51m 05s

Man-machine command output content

tracing mode common channel outgoing callee number4560034

time DPC OPC CIC H1H0 DATA14:50:44:100 1-1-1 2-2-2 63 IAM 18 00 74 54 06 30 04

14:50:44:350 2-2-2 1-1-1 63 ACM 25

14:50:46:160 2-2-2 1-1-1 63 ANC

14:50:49:230 1-1-1 2-2-2 63 CLF

14:50:49:360 2-2-2 1-1-1 63 CBK

14:50:49:470 2-2-2 1-1-1 63 RLG

Signaling tracing in the ZXJ10 switch No.7 signaling system

p378

IAM carries the called number,and caller type.

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IAM carries the called number,and caller type.

The DATA stands for the concrete information carried by the

messages. The first byte (octet) is caller type: 18 is decimal system.

It can divide into two BCD codes.

18 0001 1000

F E D C B A

0 1 1 0 0 0

From Figure 4.5.4-1 we find out that is common, used in the

local-local offices.

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The second byte is Signaling Flag (00 74)

BA--00 local call subscriber number

DC--00 connection without satellite circuit

FE--00 need not continuity test

G----0 excluding phone echo canceller

H----0 not international incoming call

I---- 0 not changing into issuing a call

J---- 0 normal call

K--- 1 all No.7 signaling channels are demanded

L--- 0 reserved

Second

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18 00 74 54 06 30 04

Digit ofcallee

is seven

First

number

Second

number third

number

fourth

number

fifthnumber

sixth

number

callee number is 4560034

last

number

2) Th f d (FSM)

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2) The forward setup message (FSM)

(1)General forward signal message (GSM).

GSM is a responding message to general request messages GRQ.

(2) Continuity test message

The continuity test message includes the continuity signal message

(COT) and the continuity failure signal message (CCF).

As common channel signals are not signals sent in voice channels, but

are signaling signals for a group of voice channels via one or several

concentrated signal links, the continuity test of voice channels are

needed to ensure the correct connection and smooth transmission of

voice channels.

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3) The backward setup request message (BSM)The general request message GRQ

GRQ contains the request type indicators, indicating that the requested

service is:

x requesting caller type

x requesting caller line label

x requesting original callee address

requesting malicious call tracingrequesting holding

requesting echo suppressor

In the process of connection, the above requests are made according

to service needs to the originating switch, which answers with GSM.

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4) The successful backward setup message (SBM)

The address complete message (ACM)

ADC: address complete, billing required;

ADN: address complete, billing free;

ADX: address complete, payphone;

AFC: address complete, subscriber idle, billing required;

APN: address complete, subscriber idle, billing free;AFX: address complete, subscriber idle, payphone.

After receiving all the called subscriber numbers and recognizing the

called subscriber status, the incoming switch immediately sends abackward setup message. In normal call connections, if the callee

subscriber is idle status, the backward address complete message ACM

shall be sent.

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8 4 40001 0100HGFEDCBA

H1 H0

BA:

00 Address complete

01 Address complete, billing

10 Address complete, billing free11 Address complete, payphone

C:

0 Callee terminal has no indication

1 Callee terminal idle

Others Not in use

Figure 4.5.4-5 Address complete signal format

E:

0 : No forward transfer for call

1 : forward transfer for call

F:

0 : any channel

1: all No.7 signaling channel

ACM 25

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ACM 25

25--------00100101

Address complete, billing

Callee terminal idle

all No.7 signaling

channels are demanded

standby

H G F E D C B A H1 H0

0 0 1 0 0 1 0 1 0001 0100

5) The unsuccessful backward setup message (UBM)

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5) The unsuccessful backward setup message (UBM)

switching equipment congestion signal SEC

circuit group congestion signal CGC

address incomplete signal ADI call failure signal CFL unallocated number signal UNN line does not service signal LDS send special information tone signal SST

access barred signal ACB digital path not provided signal DPN national network congestion signal NNC subscriber busy signal (electrical) SSB expanded unsuccessful backward setup message EUM

When the whole callee subscriber number reaches the incomingswitch, after number analysis, if the callee number is unallocatednumber, then the UNN message will be sent back.

6) Th ll i i (CSM)

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6) The call supervision message (CSM)

It includes the following signals:

answer signals, unclassified ANU

answer signal, billing required ANC

answer signal, billing free ANN

callee backward release CBK

clear forward signal CLF re-answer signal RAN

forward transfer signals (semi-automatic international call

signals) FOT

calling party clear signal CCL

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7) The circuit supervision message (CCM)

It contains the following signals:

release-guard signal RLG

blocking signal BLO

blocking acknowledgement signal BLA

unblocked signal UBL

unblocking acknowledgement signal UBA

continuity-check-request signal CCR

reset circuit signal RSC

8) The circuit group supervision message (GRM)I i l d h f ll i i l

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It includes the following signals:maintenance oriented group blocking signal MGBmaintenance oriented group blocking ack. signal MBA

maintenance oriented group unblocking signal MGUmaintenance oriented group unblocking ack. Signal MUA hardware failure oriented group blocking signal HGB hardware failure oriented group blocking ack. message HBA

hardware failure oriented group unblocking message HGU

hardware failure oriented group unblocking ack. message HUA circuit group rest GRS circuit group recovery ack GRA software generation group blocking ack. message SGB software generation group unblocking message SGU

software generation group unblocking ack. (domestic optional)SUA

9) Domestic unsuccessful backward setup message (NUB)

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9) Domestic unsuccessful backward setup message (NUB)

Subscriber local busy SLB

Subscriber toll busy STB

10) Node-to-node message (NNM)11) Circuit network management message (CNM)

The automatic congestion control message ACC12) Domestic successful backward setup message (NSB)

13) Domestic call supervision message (NCB) Traffic and signal OPR14) Unsuccessful backward setup message (NUB)

Subscriber local busy signal SLB Subscriber toll busy signal STB

15) Domestic area message (NAM) The malicious call identification signal MAL The caller re-off-hooking signal CRA

ISUP signaling message and parameter

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ISUP provides signaling basic support service and supplementservice for voice service and non-voice service.

ISUP can use MTP also can use SCCP to send message

between ISUP.

ISUP can realize all the function of TUP.

All the messages can be classified into the

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All the messages can be classified into the

following kinds according to the function:

1.call setup message : includes the request for call setup, information transferof supplementary call setup, information transfer during call setup process,

response from called user, transfer of line continuity test results when necessary,

etc.

2. In-communication message : includes call suspension, recovery,conversion in calls, messages used by operators during communication, etc.

3.call release message : the message used to release calls upon call completion.

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4.line monitoring message : includes monitoring messages used when line(suspend the use of line temporarily) is blocked for maintenance and test, when circuit is

initialized (compelled release) in case of failure, and when continuity test is performed.

5.line group monitoring message : includes messages of simultaneous blockingof line groups (up to 256 lines can be specified), initialization preset and line state detection

on a timing-basis.

6.supplementary service and other messages : includes using the messagesrelated to the request, acknowledgement, and rejection of supplementary services, transferringthe end-to-end signaling messages and user-to-user signaling.

Type Message name Code Basic function

Call

Initial address message (IAM) 00000001 The request for call setup

Subsequent address message (SAM) Inform subsequent address information

Continuity message (COT) 00000101 Inform the information channel continuity test is

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establishment completedInformation request message (INR) 00000011 The request for additional call setup information

Information message (INF) 00000100 The additional call setup information

Address complete message (ACM) 00000110 The notice of address message receiving complete

Call progress message (CPG) 00101100 The notice of call setup process

Answer message (ANM) 00001001 The information of answer from called user

Connection message (CON) 000000111 With the ACM+ANM function

In

communicatio

n

Suspend message (SUS) 00001101 The request for call suspension

Recover message (RES) 00001110 The request for recovering suspended calls

Call modification request message (CMR) 00011100 The request for modifying call features in a call

Call modification complete message (CMC) 00011101 The information of completing to modify call features

Call modification rejected message (CMRJ) 00011110 The information of rejecting to modify call features

in a callForward information (FOT) 00001000 The call request from operator

Call release Release message (REL) 00001100 The request for call release

Release complete message (RLC) 00010000 The request for call release complete

Line

monitoring

Continuity check request message (CCR) 00010001 The request for continuity testRestore circuit message (RSC) 00010010 The request for circuit initialization

Block message (BLO) 00010011 The request for circuit blocking

Unblock message (UBL) 00010100 The request for unblocking circuit

Block acknowledgement message (BLA) 00010101 Circuit blocking acknowledgement

Unblock acknowledgement message (UBA) 00010110 Circuit unblocking acknowledgement

Line group

monitoring

Circuit group block message (CGB) 00011000 The request for circuit group blocking

Circuit group unblock message (CGU) 00011001 The request for circuit group unblocking

Circuit group blockacknowledgement message 00011010 Circuit group blocking acknowledgement

Circuit group unblockacknowledgement Circuit group unblocking acknowledgement

Circuit group restoration message (GRS) 00010111 The request for circuit group initialization

Circuit group restoration acknowledgement 00101001 Circuit group initialization acknowledgement

Circuit group query message (CQM) 00101010 The message of querying circuit group state

Circuit group query response message (CQR) 00101011 The notice of circuit group state

Suppliementar

y services and

others

Performance acceptance message (FAA) 00100000 The request for allowing supplementary services

Performance request message (FAR) 00011111 The request for supplementary services

Performance rejection message (FRJ) 00100001 The request for rejecting supplementary services

Passing message (PAM) 00010100 Transfer information along with signal routeUser-to-user message USR 00101101 User-to-user signaling transfer


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For TUPD C B A

0 1 0 0

D C B A

0 1 0 1


8 16 8n(n2) 8 2 6 1 7 1 7 8 The first transmitted bits

SSI SI

SI H1 H0 label

CIC SLS OPC D PC7 Route label 0

CIC

Message type code

Necessary fixed part

Necessary variable part

Random part

integer multiples of octets

For ISUP

Routing label

Circuit identification code

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Compulsory fixed part

Compulsory variable part

Optional part

Optional part

Message type cpde

Compulsory fixed parameter A

Mandatory fixed parameter F

Pointer to variable parameter M (point to parameterM)

Pointer to variable parameter P (point to parameter P)

Pointer to start of optional part (point to the first optional parameter)

Length indicator of variable parameter M

Variable parameter M

Length indicator of variable parameter P

Variable parameter P

Variable parameter name X

Length indicator of optional parameter X

Optional parameter X

Optional parameter name Z

Length indicator of optional parameter Z

Optional parameter Z

End of optional parameters

General format of ISUP message

Route label

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SLS OPC DPC

8 24/14 24/14

DPC: destination point code OPC

SLS: signaling link select, selection for signaling link of load

share,presently only lower 4 bits used, higher 4bits standby

Route label

CIC

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7 6 5 4 3 2 1 0

CIC lowest efficient bits

Standby CIC highest efficient bits

ISUP has 2 octets to be as CIC

It is identification code for the circuits between OPC and

DPC only use lower 12 bits now higher 4 bits

standby . (coding method same as TUP )

1

2

Message type code

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g yp

defines the label of each ISUP message in a unified

mannerCompulsory fixed part

Compulsory variable part

be compulsory for a specific message and the length of

parameter should be fixed.

compulsory for specific messages but the lengths of

parameters are variable. So pointer must be used to

indicate the number of octet between the pointer and the

first octet given by each parameter value.

optional part

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optional part

For a specific message, optional part may or may not exist. If it

exists, each parameter should include parameter name, lengthindicatorand parametercontents.

Length indicator code

Indicating the byte number of parameter.

Pointer code

Occupy 1 octet indicate the number of octet between the

pointer and the first octet pointed by the pointer (included)

given by each parameter value.

ISUP message example---IAM

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ISUP message example IAM

IAM00 60 00 0A 03 02 08 06 81 90 54 48 41 03 0A 07 83 13 52

54 08 50 06 08 01 80 00

(Parameters) (type)

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(Parameters)

()(type)

(Octet)

Message type 2.1 F 1

Nature of connection indicators 2.34 F 1

Forward call indicators 2.22 F 2

Calling party's category 2.10 F 1

Transmission medium requirement 2.53 F 1

Called party number (Note 2) 2.8 V 4-?(4-11)

Transit network selection (nationaluse)

2.52 O 4-?

Call reference (national use) 2.7 O 7(8)

Calling party number (Note 2) 2.9 O 4-?(4-12)

Optional forward call

indicators

2.37 O 3

06 no7 theory

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