Configuring Extensions and the Dial Plan

The dial plan of your Cisco CME system is composed of the following components:

• Plain old telephone service (POTS) dial peers
• Voice over IP (VoIP) dial peers
• Extensions
• Digit manipulation features

The following sections describe configuring these components.

POTS Dial Peers

POTS dial peers are router configuration structures that point calls to a particular voice interface based on whether the dialed number matches certain criteria (as specified in the dial peer's destination-pattern). The voice interface can be a PSTN trunk, an analog phone, a fax machine, or an IP phone. Example 14-2 shows several sample POTS dial peers, including some for PSTN trunks and one for an analog phone or fax machine.

Example 14-2. POTS Dial Peer Examples

router#show running-config !11-digit long-distance PSTN dialing with an access code of 9 dial-peer voice 1 pots preference 1 destination-pattern 91.......... port 2/0:23 forward-digits 11 ! !7-digit local PSTN dialing with an access code of 9 dial-peer voice 4 pots destination-pattern 9[2-9]...... port 2/0:23 forward-digits 7 ! !Analog phone or fax machine dial-peer voice 2701 pots destination-pattern 2701 port 2/0/0

VoIP Dial Peers

VoIP dial peers are router configuration structures that point calls to a particular IP interface based on the same criteria that are used for POTS dial peers (that is, matching the dialed number to the dial peer's destination-pattern). IP interfaces can be H.323 or Session Initiation Protocol (SIP). Example 14-3 shows an H.323 dial peer that directs calls to another site where all the extensions start with three.

Example 14-3. VoIP Dial Peer Examples

router#show running-config dial-peer voice 3000 voip destination-pattern 3... session target ipv4:172.19.153.41 dtmf-relay h245-alphanumeric codec g711ulaw no vad

Extensions

You can configure the extensions defined for your IP phones either by using the GUI or directly on the router using the ephone-dn command. As covered in Chapter 5, "Cisco CME Call Processing Features," an ephone-dn has two components:

• A virtual POTS dial peer for directing calls to the phone
• A virtual voice port

Note

The voice ports and dial peers automatically generated by ephone-dns do not appear on the Cisco CME running configuration. They can be seen only using more specific show commands.

Example 14-4 shows the definition on an ephone-dn and its associated POTS dial peer and voice port.

Example 14-4. Ephone-dn Dial Peer Example

router#show running-config ephone-dn 1 number 3001 description User1 name User1 call-forward busy 3105 call-forward noan 3105 timeout 10 ! router#show telephony-service dial-peer dial-peer voice 20001 pots destination-pattern 3001 huntstop call-forward busy 3105 call-forward noan 3105 ! router#show telephony-service voice-port voice-port 50/0/1 station-id number 3001 station-id name User1 timeout ringing 10 progress_ind setup enable 3 port 50/0/1

Digit Manipulation Features

Having an internal dial plan such as calling from one IP phone to another using a short extension of three or four digits, while also calling the outside world through the PSTN using fully qualified E.164 numbers, requires a certain amount of digit manipulation to add or subtract leading digits to or from an extension.

Typically, you have a trunk access code for an IP phone user to specify that a call should be routed to the PSTN as opposed to another extension. This access code must be translated to a PSTN-recognizable number before delivering the call to the PSTN. In Example 14-2 you saw 9 used as the PSTN access code. Because this number matches the dial peer destination-pattern explicitly, it is deleted from the digit string forwarded to the PSTN. You can also see forward-digits commands in those POTS dial peers. These control how many of the numbers dialed by the IP phone user are forwarded to the PSTN, thereby offering simple digit manipulation within the dial peer statement itself.

Chapter 6 covered more sophisticated digit manipulation features available in Cisco CME, such as dialplan-patterns and Cisco IOS translation rules.

Other Cisco CME Dial Plan Features

Various other types of DNs or extensions also make up part of your dial plan in the sense that defining these features requires the definition of digits to dial to activate the feature. These features include speed dial, intercom, call park, and paging.

There are also other special types of numbers, such as the AA and voice mail pilot numbers, as well as MWI DNs. The transfer-pattern feature also plays a role in your dialing plan, because this definition determines what numbers your IP phone users can transfer calls to.

Class of Restriction (COR) and call blocking are features that determine which numbers might not be dialed on the system.

Note

Dial plans are a wide topic that extends well beyond the scope of Cisco CME. All the different ways you can configure dial plans are beyond the scope of this book.