SIP to PSTN(FXO) failover

[rajithahettiarachchi]

Hello,

I have a SIP line connected to my Cisco 2921 voice router. Also there are two PSTN lines connected to Router via FXO ports. I want to configure these FXO ports to work when SIP line is down. I have already configured it, but when SIP is down calls goes through only one PSTN line and users can't make calls(busy signal). How can i configure to use two PSTN line.

ex - If one PSTN line is busy, a call must go through the other PSTN line.

[rajithahettiarachchi]

Please find the configuration that I have done

!
voice-port 0/0/1
supervisory disconnect dualtone mid-call
supervisory custom-cptone AE-Custom
supervisory dualtone-detect-params 1
timeouts call-disconnect 1
timeouts wait-release 1
timing hookflash-out 50
connection plar opx immediate 0
caller-id enable
!

!
voice-port 0/0/3
supervisory disconnect dualtone mid-call
supervisory custom-cptone AE-Custom
supervisory dualtone-detect-params 1
timeouts call-disconnect 1
timeouts wait-release 1
timing hookflash-out 50
connection plar opx immediate 0
caller-id enable
!



!
dial-peer voice 402 voip
description Outgoing Dial-peer To SIP SP LD
translation-profile outgoing STRIP9
preference 1
destination-pattern 90[1-9]........
session protocol sipv2
session target ipv4:172.16.1.1
voice-class codec 1
max-redirects 5
dtmf-relay rtp-nte digit-drop
no vad
!

!
dial-peer voice 4 pots
translation-profile outgoing STRIP9
preference 2
destination-pattern 90[1-9]........
port 0/0/3
forward-digits 10
!

!
dial-peer voice 6 pots
translation-profile outgoing STRIP9
preference 3
destination-pattern 90[1-9]........
port 0/0/1
forward-digits 10
!