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Aug 15

SRST Sample Config

In this post I am going to explain a sample config that can be used for SRST Config. This config can be used in a scenario where we want to provide some fall back support for phones on a remote when link to Primary and Secondary Call Manager is no longer available. Now, if the WAN link breaks the router will have SRST configured and will able to accept phone registrations. The config is explained below

 
 
!
dial-peer voice 12 voip
 description *** From PSTN – Primary CM ***
 preference 1
The preference is 1 here to make this dial peer  more preferred. The default value is zero, the lower the value, the higher the priority.
 destination-pattern 888…
 voice-class codec 1
 voice-class h323 1
 session target ipv4:192.168.1.1
 incoming called-number .
 dtmf-relay cisco-rtp h245-signal h245-alphanumeric
 ip qos dscp cs3 signaling
 no vad
This voip dial peer is used for Primary CM.
!
dial-peer voice 13 voip
 description *** From PSTN –  Secondary CM ***
  preference 2
The preference is 2 here to make this dial peer the second preferred. The default value is zero, the lower the value, the higher the priority.
 destination-pattern 888…
 voice-class codec 1
 voice-class h323 1
 session target ipv4:192.168.1.2
 incoming called-number .
 dtmf-relay cisco-rtp h245-signal h245-alphanumeric
 ip qos dscp cs3 signaling
 no vad
This voip dial peer is used for Secondary CM.
!
dial-peer voice 14 voip
 description *** From PSTN –  SRST ***
 preference 3
The preference is 3 here to make this dial peer the third preferred.This will make sure the Call Managers are tried first for availability before this dial peer is tried.
 destination-pattern 888…
 voice-class codec 1
 voice-class h323 1
 session target ipv4:192.168.1.1
IP address of the router. It can be IP address of physical interface or an HSRP address.
 incoming called-number .
 dtmf-relay cisco-rtp h245-signal h245-alphanumeric
 ip qos dscp cs3 signaling
 no vad
 
!
!
call-manager-fallback
 max-conferences 4 gain -6
 timeouts interdigit 3
 ip source-address 192.168.1.1 port 2000
 max-ephones 48
 max-dn 96
 keepalive 120
 time-format 24
 date-format dd-mm-yy
This is SRST specific config. The number of max-ehone depends on the licenses you have purchased and the model of router being used.
 

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