lecture 6 - dial plans part 1

8/18/2019 Lecture 6 - Dial Plans Part 1

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1Voice Over IP: Chapters 4 and 5 – Introducing and Implementing Dial Plans Josh Lowe – Winter 2012

Introducing andImplementing DialPlans

Chapters 4 and 5


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NUMBERING PLANFUNDAMENTALS


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Introducing Numbering Plans

A numbering plan defines rules for assigning numbersto a device

There are private numbering plans and public (orPSTN) numbering plans

Private numbering plans are used to address endpointsand applications within private networks

Private numbering plans are not required to adhere to

any specific format PSTN or public numbering plans are unique to the

country in which they are implemented


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North American Numbering Plan

The North American Numbering Plan (NANP) is atelephone numbering plan that serves 20 North

American countries

NANP numbers are ten-digit numbers, usually

formatted as NXX-NXX-XXXX, in which N is any digitfrom 2 through 9 and X is any digit from 0 through 9


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North American Numbering Plan

The first three digits of an NANP number (NXX) arecalled the Numbering Plan Area (NPA) code, oftencalled the area code

The second three digits (NXX) are called the central

office (CO) code, switch code, prefix, or exchange code

The final four digits (XXXX) are called the line numberor station number


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NANP Numbering Assignments

There are 800 possible combinations of area codeswith the NXX format

There are some numbers reserved for special purposes

For example, Easily Recognizable Codes (ERC) areany area code where the second and third digits are thesame (e.g. 800, 866, 877, 888, etc.)

They are used for special features like toll-free dialing

Another example, 011 is the international exit codeused before dialing an international number


7/457Voice Over IP: Chapters 4 and 5 – Introducing and Implementing Dial Plans Josh Lowe – Winter 2012

NANP Numbering Assignments

Long distance calls (within the NANP) start with thenumber 1, called the country code

A seven-digit number usually defines a local call in theformat XX-XXXX, although many larger areas

use ten-digit local numbers instead of seven There are also eight N11 codes, called service codes,

that are not used as area codes

For example, 911 is used for emergency services, 411

is used for directory services, and 611 is used for repairservices

There are additional reserved numbers for things likeTelecommunications Relay Service (TRS) and 1-900premium services



Fixed and Variable-Length Numbering PlanComparison



E.164 Addressing

E.164 is an international numbering plan for publictelephone systems

Each assigned number contains a one-, two-, or three-digit country code (CC), followed by a national

destination code (NDC), and then by a subscribernumber (SN)

An E.164 number can have as many as 15 digits



E.164 Addressing

In the E.164 plan each address is unique worldwide

With as many as 15 digits possible in a number, thereare 100 trillion possible E.164 phone numbers



Hierarchical Numbering Plans

Provides scalability to endpoint addressing



Basic Call Types

Local calls occur between two telephones connectedto one Cisco voice-enabled router

This type of call is handled entirely by the router anddoes not travel over an external network



Basic Call Types

On-net calls occur between two telephones on thesame data network (over the WAN)

The calls can be routed through one or more Ciscovoice-enabled routers, but the calls remain on the same

data network



Basic Call Types

Off-Net Calls are calls that travel through othernetworks, such as the PSTN

To gain access to the PSTN, the user dials an accesscode, such as 9, from a telephone directly connected to

a Cisco voice-enabled router or PBX



Basic Call Types

PLAR calls automatically connect a telephone to asecond telephone when the first telephone goes offhook

The user does not get a dial tone, because the voice-

enabled port that the telephone is connected to ispreconfigured with a specific number to dial



Basic Call Types

PBX-to-PBX calls originate at a PBX at one site andterminate at a PBX at another site while using thenetwork as the transport between the two locations

Many business environments connect sites with private

tie trunks



Basic Call Types

An On-Net to Off-Net Call originates on an internalnetwork and is routed to an external network, usually tothe PSTN

On-net to off-net call-switching functionality might be

necessary when a network link is down



Non-Overlapping Numbering Plan

A dial plan can be designed so that all extensionswithin the system are reached in a uniform way

Uniform dialing is desirable because of its simplicity



Overlapping Numbering Plans



Overlapping Numbering Plans

The most common solution to the overlap problem innumbering plans is to use site codes

An intersite prefix (8, in this example) indicates that acall is being sent to a different site, and the site code

determines which site


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Private Number Plan ImplementationExample



DIAL PLAN COMPONENTS



Endpoint Addressing Considerations

Reachability of internal destinations is provided byassigning directory numbers to all endpoints andapplications

The most common issue with endpoint addressing is

related to the mapping of internal extensions toavailable DID ranges assigned by the PSTN

An auto-attendant can be used to route calls betweenthe PSTN and the internal network when there are not

enough DID numbers to cover the internal addressscope


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PSTN Dial Plan Requirements

Inbound PSTN Calls:

Inbound call routing includes digit manipulation to ensure thatan incoming called number matches the pattern expected bythe final destination


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Both the called and calling numbers must betransformed inbound:

The called number can be converted from the public E.164format to the internal number used for internal dialing

The calling number must be presented to the callee in a waythat allows callback


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Outbound PSTN Calls:

Outbound calls might require digit manipulation to modify acalled number according to PSTN requirements. This outboundcall routing usually includes stripping of any PSTN access codethat might be included in the original called number


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Both the called and calling numbers must betransformed outbound:

The called number processing involves the stripping of theaccess code

The calling number must be converted from the internalextension to the public E.164 format


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Secondary Paths


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Call Coverage

Call coverage features are used to ensure that allincoming calls to CUCME are answered by someone,regardless of whether the called number is busy ordoes not answer

Cisco voice gateways offer a variety of call coveragefeatures


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Call Coverage

Call forwarding: Calls are automatically diverted to adesignated number on busy, no answer (noan), allcalls, or only during night-service hours

Hunt group: The system automatically searches for an

available directory number from a matching group ofdirectory numbers until the call is answered or the huntis stopped

Call pickup: Calls to unstaffed phones can be

answered by other phone users using a softkey or bydialing a short code


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Call Coverage

Call waiting: Calls to busy numbers are presented tophone users, giving them the option to answer or letthem be forwarded

Basic automatic call distribution (B-ACD): Calls to a

pilot number are automatically answered by aninteractive application that presents callers with a menuof choices before sending them to a queue for a huntgroup

Night service: Calls to phones not staffed during aparticular time of the day can be answered by otherphones

Overlaid ephone-dn: Calls to several numbers can be

answered by a single agent or multiple agents


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CLASS OF RESTRICTION(COR)


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Class of Restriction

Class of Restriction (COR) is a feature that allowscalling privileges to be assigned

The COR feature provides the capability to deny certaincall attempts based on the incoming and outgoing

CORs provisioned on the dial peers and ephones

COR is used to specify which incoming dial peer (orephone) can use which outgoing dial peer to make acall


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Class of Restriction

Incoming COR Outgoing COR

or or

The incoming COR (applied to ephone-DNs or inbounddial-peers) is like having one or more keys

The lack of an incoming COR is like having a master

key that can unlock all locks

The outgoing COR (applied to dial-peers) is like a lockor locks

The lack of an outgoing COR is like having no lock


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Class of Restriction – Case Study

dial-peer cor custom

name 911

name local

name long_distance

name international

name 900

911

local

long_distance

international

900

Step 1 - Define the classes of restriction


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dial-peer cor list call911 member 911

dial-peer cor list callLocal

member local

dial-peer cor list callLD

member long_distance

dial-peer cor list callInt

member international

dial-peer cor list call900

member 900

dial-peer cor list Lobby member 911

dial-peer cor list Employee

member 911

member local

dial-peer cor list Sales

member 911

member local


dial-peer cor list Executive

member 911

member local member long_distance


Step 2 – Define the COR lists and members


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dial-peer voice 1 pots

destination-pattern 911

port 1/0/0

corlist outgoing call911


destination-pattern 1[2-9]..[2-9]......

port 1/0/0

corlist outgoing callLDdial-peer voice 3 pots

destination-pattern [2-9]......

port 1/0/0

corlist outgoing callLocal


destination-pattern 011T

port 1/0/0

corlist outgoing callInt


destination-pattern 1900.......

port 1/0/0

corlist outgoing call900

Dial-peer 1 – COR out call911

Dial-peer 2 –

COR out callLD

Dial-peer 3 – COR out callLocal

Dial-peer 4 – COR out callInt

Dial-peer 5 – COR out call900

Step 3 – Assign the outgoingCOR to the PSTN dial-peers


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ephone-dn 1

number 1001

cor incoming Lobby

ephone-dn 2number 1002

cor incoming Employee

ephone-dn 3

number 1003

cor incoming Salesephone-dn 4

number 1004

cor incoming Executive

Ephone-dn 1COR in Lobby

Ext 1001

Ephone-dn 2COR in Employee

Ext 1002

Ephone-dn 3

COR in SalesExt 1003

Ephone-dn 4COR in Executive

Ext 1004

Step 4

– Assign the incoming COR to the ephone-dns


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Ephone-dn 1COR in: Lobby

Results:

The Lobby ephone-dn can only call911 on the PSTN

dial-peer cor list Lobby

member 911

Dial-peer 1 – COR out: call911

Dial-peer 2 –

COR out: callLD

Dial-peer 3 – COR out: callLocal

Dial-peer 4 – COR out: callInt


member 911


member local


member 900


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Results:

The Employee ephone-dn can call911 and local calls on the PSTN

dial-peer cor list Employee

member 911 member local


Dial-peer 2 –

COR out: callLD




member 911


member local


member 900

Ephone-dn 2COR in: Employee


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Results:

The Sales ephone-dn can call 911,local calls, and long distance on thePSTN

dial-peer cor list Sales

member 911

member local



Dial-peer 2 –

COR out: callLD




member 911


member local


member 900

Ephone-dn 3COR in: Sales


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Results:

The Executive ephone-dn can call911, local calls, long distance, andinternational on the PSTN

dial-peer cor list Executive

member 911

member local




Dial-peer 2 –

COR out: callLD




member 911


member local


member 900

Ephone-dn 4COR in: Executive


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Nobody can call 1-900 numbers

Remember : no incoming COR on an ephone is the same as having a master key!


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lecture 6 - dial plans part 1

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