Sharing Provider SIP Trunk or E1 between two or more UCMs


I have 3 UCMS 1x6510, 2x6202. I have a SIP provider who has terminated a SIP trunk to the UCM6510 WAN port and it works great. I want to share the trunk with my other 2 UCMs which are linked to the 6510 via a Peer SIP trunk. Does Grandstream support this setup?


You need use DID feature with allowing trunk. Then prepare correct inbound/outband between each trunk.


You may find this cocument to be of use.

Also, this video may help



This one I have already done. I have an existing Peer SIP trunk between the 3 UCMs and works well.Challenge is sharing the Provider SIP trunk which is at 6510.

Could you have a step by step guide maybe you can refer me to? I don’t understand which UCM to enable CID and which to have the inbound/outbound


@Kzioliver, it has been a while since I saw this video, and I may be comfusing it with another, but AFAIR it shows you how to do what you are asking; make a call form a remote UCM which goes out form a remote UCM’s trunk. My applogies in advance if I am suffering from a “senior moment” and have confused this video with another.


@drostoker Thanks! That worked. Just to confirm, this should work even if I have multiple provider SIP trunks registered on the 6510 as well? Thanks a lot.
Sorry I didn’t notice the video. It looked like a footer to me, at first glance :joy:


Yes, It all depends on how your configure your Inbound and Outbound routes.


In short: you need know what you forward where.
You will need correctly set outband so call will be forwarder to correct trunk.