SIP Trunk failover circuit

[Mark Verwey]

I have a small office that we have implemented SIP trunks with Centurylink and a broadband circuit.  For their call volume it works great.  We are looking for a failover or HA solution because the main circuit has gone out a couple of times and when that happens they aren't able to make a call unless they use a cell phone until the circuit comes back up.  I was thinking a cradle point for the backup circuit would work on 4G to allow them at least 1 or 2 simultaneous calls so they could at least have a way to call out in the event of an emergency.  My question/problem is we have a 2951 with a cube license, how would I set this up to handle both circuits and auto switch over to the cradle point when the primary broadband goes down then auto switch back when the broadband comes back online.  Our SIP provider has the ability to check and attempt to send call to the primary circuit (broad band) and if its IP isn't reachable send it to a secondary circuit.  It will check on each call inbound.  Outbound it would care which circuit/path it came from it would send it accordingly. 

[Hari Prasad]

Hello Mark,

Can you explain the Call Flow. It is not mentioned that you are using CUCM or other PBX system or 2951 router as CME.

Please mention the call flow for outbound call and share show run from 2951 router.

[Mark Verwey]

Call flow is as follows:

incoming call PSTN <=> SIP Carrier <=> Broadband circuit <=> Cisco 2951 CUBE <=> PBX (Avaya IP Office)

I have this working now, with no failover circuit.  I am wanting to add a cradlepoint CBA850LPE as the failover circuit.  It will allow at least 1 call out across its 4G bandwidth when the primary bb circuit goes down, so below is kind of what I want the final out come to be:

PSTN <=> SIP Carrier <=> Broadband, if unreachable send to cradlepoint <=> 2951 <=> PBX.  the PBX connects to g0/0, BB connects to g0/1, and the cradlepoint will connect to g0/2.  Other info on the SIP connection with the provider, they are requiring authentication and this is being handled by the 2951 and the PBX.  I will also need to figure out how to change the bind statements so that when using the primary BB it looks at g0/1, but when on the failover it changes to the g0/2 port.