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SIP Max-Forwards and CCM


I have a client using SIP trunks with a provider, and some inbound calls come in with a low Max-Forwards value and other calls come in with a higher value. At night, they forward their phone to cell phone and if the call comes in with a low max-forwards value of 8 the CCM is simply redirecting the call and decrementing the Max-Forwards value by 1 so it is 7 and sending it back out the SIP trunk. The providers switch decrements it by 1 making it 6, then passes it to their TDM equipment for PSTN Handoff which divides the Max-Forwards value by 3 making it 2 and there isn't enough hops to get to the destination and the call fails.

Does any one know how to handle this situation on the CCM side?

We have worked with the provider and they can't control where the inbound calls come into them and the Max-Forwards value since it is coming from other providers.

I have tried to forward the call out another SIP trunk which goes to same provider, but CCM treats the call forward as a redirect still. I have also tried Mobility (Remote Destination) and that triggers a new call over the SIP trunk with Max-Forwards value of 70 and the call connects but there is no audio passed either way.

This is on CCM 6.1.2.


Re: SIP Max-Forwards and CCM

This is bug CSCee61062 One way audio after IP phone SIP blind transfer. This header field must be used with any SIP method to limit the number of proxies or gateways that can forward the request to the next downstream server. This can also be useful when the client is attempting to trace a request chain that appears to be failing or looping in mid-chain. The Max-Forwards value is an integer in the range 0 to 255 indicating the remaining number of times this request message is allowed to be forwarded. This count is decremented by each server that forwards the request. The recommended initial value is 70. This field should be inserted by elements that can not otherwise guarantee loop detection.