SRST Site Phones Not Falling Back During WAN Failure – Centralized SIP

[James Poff]

Hi everybody,

We're running into a problem with SRST fallback in our CUCM deployment,
Phones should detect CUCM unreachable and fall back to local SRST,
and Outbound calls during fallback should use local FXO via SRST CUBE dial-peer,

but
Phones fail to register during WAN outage
and "Unprovisioned" message or stuck in "Registering..."
also Debugs on SRST router show no registration attempts

how can i fix this issue ?
where is the problem ?

[Mohammadreza Hadi]

Hi @James Poff 

what is your SRST config on router ?
please share with us here..

[James Poff]

this is a section of my config, which is related to SRST:

voice service voip
allow-connections sip to sip
!

call-manager-fallback
max-ephones 10
max-dn 10
ip source-address 192.168.10.110 port 2000
timeouts restart 10
!

interface GigabitEthernet0/1
ip address 192.168.10.110 255.255.255.0
!

[Mohammadreza Hadi · Accepted solution]

make sure >>
ip source-address 192.168.10.110 match the LAN IP of the router (reachable by phones)
and max-ephones and max-dn be sufficient for the site.. 

[Mohammadreza Hadi]

also, on CUCM, Confirm Phones Have Correct SRST Reference

Go to Device Pool > SRST Reference

Ensure it points to the branch router IP address

The IP must match the interface the phone reaches via LAN during fallback

and verify >>

Phone’s Device Pool includes this SRST reference

Under Device > Phone, scroll down to SRST info and confirm it is populated..

[James Poff]

thanks @Mohammadreza Hadi 

problem is fix now
issue was from phones which they can not reach router lan ip address