For a cost effective alternative SBC that would work with Transnexus, you could look into dSIPRouter

Are you using the paid version for Bria? The “free” Solo version is unable to transfer calls

You are going to have to channel your request here

Lenny?

Did they indicate that open source dev on Kazoo would still be on going? Or are they closing this out?

I wouldn’t recommend having your call center agents work of their mobile due to often flaky mobile Internet here on the continent. For mostly inbound calls, any local VoIP provider should be able to meet your needs. You’d need to port your business number to VoIP if it isn’t already voip

VoIP numbers won’t be of any help with that I’m afraid

Playing with Freepbx? Have a look at Signalwire for SIP trunk.