Specifications

Configuration Tasks
28
Cisco IOS Release 12.0(3)T
VoIP—VoIP dial peers describe the line characteristics usually associated with a packet network
connection (in the case of VoIP, this is an IP network). VoIP peers define the line characteristics
between VoIP devices—the routers and access servers carrying voice traffic in this voice network.
Inbound versus Outbound Dial Peers
Dial peers are used for both inbound and outbound call legs. It is important to remember that these
terms are defined from the access server’s perspective. An inbound call leg originates outside the
access server. An outbound call leg originates from the access server.
For inbound call legs, a dial peer might be associated to the calling number or the port designation.
Outbound call legs always have a dial peer associated with them. The destination pattern is used to
identify the outbound dial peer. The call is associated with the outbound dial peer at setup time.
POTS peers associate a telephone number with a particular voice port so that incoming calls for that
telephone number can be received and outgoing calls can be placed. VoIP peers point to specific
devices (by associating destination telephone numbers with a specific IP address) so that incoming
calls can be received and outgoing calls can be placed. Both POTS and VoIP peers are needed to
establish Voice over IP connections.
Establishing communication using Voice over IP is similar to configuring an IP static route: you are
establishing a specific voice connection between two defined endpoints. As shown in Figure 7, for
outgoing calls (from the perspective of the POTS dial peer 1), the POTS dial peer establishes the
source (via the originating telephone number or voice port) of the call. The VoIP dial peer establishes
the destination by associating the destination phone number with a specific IP address.
Figure 7 Outgoing Calls from the Perspective of POTS Dial Peer 1
To configure call connectivity between the source and destination as illustrated in Figure 7, enter the
following commands on router 10.1.2.2:
dial-peer voice 1 pots
destination-pattern 1408526....
port 0:D
dial-peer voice 2 voip
destination-pattern 1310520....
session target ipv4:10.1.1.2
In the previous configuration example, the last four digits in the VoIP dial peer’s destination pattern
were replaced with wildcards, which means that from router 10.1.2.2, calling any number string that
begins with the digits “1310520” plus four digits will result in a connection to router 10.1.1.2. By
implication, configuring the destination pattern this way means that router 10.1.1.2 services all
numbers beginning with those digits. From router 10.1.1.2, calling any number string that begins
with the digits “1408526” will result in a connection to router 10.1.2.2. By implication, configuring
10355
(408) 526....
(310) 520....
10.1.2.2
Source Destination
10.1.1.2
Voice port
0:D
Voice port
0:D
IP cloud
Source router
VoIP call leg
POTS call leg