Herein lies the issue, since we want the call to timeout to a vm box within the nbx rather than on the cell service. Obviously, the caller can only leave a vm on the cell phone atm.
Anyway, is there another possiblity or is this a simple technical limitation?
Not sure if I understand what you are trying to do but I think this is it :
If I read this correctly , there is a forward to voicemail option that works only on a tel and not on an external call .
It will bring the caller back to the mailbox after the timeout . I do not know of a way to ring back to the mailbox after the call is sent to an external number ......