I've managed to do something similar and for incoming work very well, only think is that it is not possible to use it as an outgoing trunk, I've always to call the extension and then after the tone of GoIP gate I need to dial out.
Not 100% clean but work... what it is not clear to me is the so call trunk mode of this device that doesn't seems to work as a real voip trunk...
I just received a GoIP - 100 single channel GSM gateway/adapter. I would like to configure it to route all incoming calls on the GSM to pbxes. Can anyone help me go about that. I guess I will need to set up a sub pbx or a extension for that. I've got other extensions and softphones working fine but this is something new and hard to find documentation.