Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Sip trunk failover question


Setup - 3845 router with sip trunk to A-Z Provider plus 1 x 30 channel PRI.

I have calls working fine over the Sip trunk and have mulitple dial-peers with preferences. However the failover only seems to work if the sip trunk is down. If the call is sent to the provider and it fails the router doesnt failover to the other dial-peer preference ie local isdn.

Is it possible to get failover working on congestion or some other sip response code other than the sip trunk being down?




Re: Sip trunk failover question

Hi Taff

i am not sure from the bellow solution but if you can give it go

if the SIP ISP give limited number of calls lets say max 30 or 40 for example

in the sip voip dial-peer to the ISP use the command max conn 30 or 40 based on the max number of calls allowed by the ISP

in this way you will limit the voip dial-peer to the ISP to a certain number of calls if that number reached, you would expect the call to try other dial peers with higher preference number

good luck

New Member

Re: Sip trunk failover question

Thanks for the reply but i'm looking more for a sip response code such as congestion or channel unavailable to then throw the call back to the router for local isdn termination.

New Member

Re: Sip trunk failover question


Depending on the SIP Response you're receiving from the ITSP the IOS Gateway may or may not re-route the call.  IOS will only re-route on specific cause codes.  I tried locating the document that called out the exact ISDN and SIP cause codes that would re-route a call, but couldn't find it.

Don't forget that you can also manipulate the SIP response / cause code values under sip-ua.

Couple links for you:

I hope this information helps or at least gets you in the right direction.


New Member

Re: Sip trunk failover question

Thanks i'll take a look..

CreatePlease login to create content