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Trunk reinvite for specific trunks

Hubertus R.

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Hello all,


in my setup I have to offices served by one SnomOne PBX but two gateways. So in Location A I have my server and one PSTN gateway. In location B, connected via Tunnel, I have a few user and a small PSTN gateway. The calls from this small gateway are usually routed to the extensions also located in location B. Due to the behavior of SnomOne there should usually be no reinvite to the trunk. So the call for instance comes in at location B, goes to the PBX through the tunnel and is then returned through the tunnel to the extension. This causes 2 sip traffic streams through the tunnel. I found now http://forum.snomone.com/index.php?/topic/6206-what-do-these-parameters-specifically-control/ and the note regarding the possibility to enable reinvites for trunks. So for my understanding this should avoid the unnecessary load on the tunnel and connect the gateway and extension in location B directly for the audio stream.


Am I right and is there a way to enable the trunk reinvite option only for specific trunks?




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We have this topic from time to time. For example Asterisk supports it, there is something like canreinvite=true/false/maybe and so on. The problem with that is that it is difficult to get it working (getting trunks working at all is already difficult) and we made the decision at the time to keep trunks on the SIP level really as simple as possible. I know from a architectural point of view it is madness; however keep in mind people want to be able to record calls or hit ## to get back to the dial tone (from the cell phone). Those features are extremely difficult to implement if the PBX does not stay in the media path.


In addition to that, even if a SIP trunk provider seems to support it, we have made the experience that SIP trunk provider interoperability is not a static thing. It might even depend on who you are calling (next tier provider). This is something you really don't want to troubleshoot.

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Thanks for the instant response. As I'm coming from the Asterisk world, I was in fact hoping for this canreinvite-option. But on the other hand your explanation does have a valid point. So far we are not using recording nor the possility for phones to call in. Our business is just not big enough. So I will for now rely on the option to use the global flag and worst case accept the double load on my tunnel.


Thanks a lot

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