We have a customer with multiple sites on the one PBX. Each site has a Ring Group to distribute their local customer calls to. If the calls to the Ring Groups are answered and then transferred to an external number, the outbound caller ID is being set as the the SIP trunk Default CPN. There is no way to set the CPN Substitution for a Ring Group and I have tried setting the DID Ranges for CPN Substitution for the Ring Group DN number but that makes no difference.
Has anyone done this and if so how did you achieve it?
