I have all my voicemails forwarded to my email.
I thought I would try substituting Google Voice for PBXes internal voice mail since Google voice puts their transcription of the message in the body of the email forwarding each voicemail.
I have tried putting my gvoice number into the field for the number to forward to. It works but the incoming caller id on the message is some strange phone number in the 626 area code.
I then tried creating a gvoice trunk in pbxes and assigning it to an outbound route to be used when a call is made to my gvoice number. No difference. Same (626) caller id shows up.