Cisco IOS Voice Dial-Peers Example

This is an example of Dial-Peers how they are configured on an Cisco IOS Gateway which is registered to CUCM.

A rule of thumb, each call has two call-legs, hence two dial-peer have to be matched with incoming and outgoing call.

! This example assumes that PRI is being used for PSTN calls. If SIP is the service used, it would be similar dial-peers but voip and some other changes like dtmf, destination IPv4, etc.


Inbound from PSTN (Dial-peers 1 and 2 below - 2 call legs)

! Incoming Dial-Peer to receive calls from outside PSTN.

dial-peer 1 pots
 incoming called-number .  ! '.' will match any digit and any preceding digits. If this was a .$ then only one digit would be matched
​ direct-inward-dial

! Other leg of the incoming call going towards CUCM
! This dial-plan assumes that telco send 4 digit calls to the customer in the format 2XXX.
​
dial-peer 2 voip
 destination-pattern 2...$
 session target ipv4:10.1.1.2 ! CUCM IP
 dtmf-relay h245-signal

Outbound from CUCM to PSTN (Dial-peers 3 to recieve calls from CUCM and rest of dial-peers to send to PSTN - 2 call legs)

! Incoming Dial-Peer to receive calls from CUCM. 

dial-peer 3 voip
 incoming called-number .
 session target ipv4:10.1.1.2 ! CUCM IP
 dtmf-relay h245-signal

! For emergency calls

! Other leg of the outgoing call going towards PSTN - based on the number dialed. One of these will be used to call PSTN.

dial-peer 911 pots
 destination-pattern 911$ 
 no digit strip <OR> prefix 911 <OR> forward-digits 3 !Anything that is explicitly matched on POTS dial-peer is removed.     ! This isn't true for VOIP. VOIP Dial-peer doesn't remove anything that is explicitly matched.
 port 0/0/0:23 
 
! 10 digit North American calls

dial-peer 9 pots
 destination-pattern 9[2-9]XX[2-9]XXXXXX$
 port 0/0/0:23
 ! no need for any prefix or any forward digits as only number explicitly matched is 9 which we want removed as its our      ! PSTN code.
 
! 11 digit North American Long Distance calls

dial-peer 91 pots
 destination-pattern  91[2-9]XX[2-9]XXXXXX$
 prefix 1 <OR> forward-digits 11 ! 1 is being explicitly matched and we want it to go out as its our long distance code used by the PSTN.
 port 0/0/0:23

! International Calls
 
dial-peer 9011 pots
 destination-pattern 9011T ! International calls dialed with # in the end would be matched too. It would be automatically matched because of the next dial-peer. Next dial-peer is default so it isn't visible in the config.
 prefix 011 ! can't use forward-digits as we don't know the extension length that would be dialed. 
 port 0/0/0:23
 
dial-peer terminator # ! Its a default command and any call with # is already a terminator for interdigit timeout, unless changed by someone.

Note: On CUCM, in Service Parameters "Strip # Sign from Called Party Number" is "True" by Default - Meaning it would remove # as the trailing number.