Has anyone added a gsm gateway like a SIM * 4 cellular GSM SIP VOIP Gateway Quad Band: ip PBX to Axon.? This I would have thought is one of the main reasons for having a voip system. We currently use a Asterisk IPPBX system with a GoIP4 unit attached. This works very well but I a keen to switch to a Windows based system so I can do the changes rather than using a specialist. We have been able to make it registrar but are really just playing around in the dark. Has anyone tried to do this.? 