Understanding Dial Peer

Dial peers are the primary used to implement a dial plan on Cisco voice gateways. Dial peers are used to determine which calls are routed and the path a call should take.

POTS dial peers are used to process calls that are connected to traditional telephony equipment such as PBX, Analog Phone and PSTN.

VOIP dial peers are used to process calls to or from the data network.

Pots Dial Peers

Configuration

Router(config)#dial-peer voice 1 pots
Router(config-dial-peer)#destination-pattern 2222
Router(config-dial-peer)#port 0/0/0

VOIP Dial Peers

Configuration

Router(config)#dial-peer voice 100 voip
Router(config-dial-peer)#destination-pattern 3333
Router(config-dial-peer)#session-target ipv4:192.168.1.1

Dial Peer Matching

Inbound and Outbound Dial Peers.

 Inbound Dial Peer Matching

Priority1 "incoming called-number" ---> Defines the called number or DNIS string

Priority2 "answer-address" ---> Defines the originating calling number or ANI string

Priority3 "destination-pattern" ---> Uses the calling number (originating or ANI string) to match the incoming call leg to an inbound dial peer.

Priority4 "port" ---> Attempts to match the configured dial-peer port to the voice port associated with the incoming call (POTS dial peers only).

Priority5 "default" dial-peer or dial peer 0, is matched when no other inbound dial peer is used. It is better to configure a specific dial peer to match incoming calls.

Outbound Dial Peer Matching

For outbound dial peer matching, the called number is matched against the configured destination-pattern in the dial peers with the longest matched.

Consider the following scenario.

R1 has 4 dial-peers configuration, 2 pots and 2 voips.

When phone 2222 call 3333,

dial-peer 2 pots will match as an inbound dial-peer because "incoming called-number" is the 1st priority when matching inbound dial-peer and the call will be processed as one-stage dialing(you will not get the second dial tone to enter additional digits).

dial-peer 101 voip will match as an outgoing dial-peer because 3333 is the longest matched and codec g.729r8 will be used for RTP media stream over ip network.