Hi
No, any combinations can be used they can be of different versions etc. all are compatible. If everything is working on LAN but not over the Internet you should not look for the problems in the Remoterig, you should look at your Routers and their settings. Sometimes even the ISP can be a problem for example they can have blocked port 5060 so must change it. But you must describe your problem better if we should be able to help.
73 de mike