As far as I know SE has no specific site to ask question about telco network like GSM/EDGE network. More of less SF deals with computer networking, system etc. Is SF an appropriate place to ask any question about Telecommunication network?
If you're asking questions about working on the telecommunications network, especially the mobile network, then certainly it's within the scope of Server Fault.
However, the problem is that it's a somewhat specialized industry and for some questions there may not be anyone here who can answer. Some questions may get no response, or be closed as too localized.
While you ask your question, keep in mind that we prefer practical questions. It's right in the FAQ: Ask questions based on actual problems that you face.
Only questions that fit the defined parameters described in the FAQ are on topic for SF. I really can't imagine any GSM/EDGE questions meeting those criteria but if they do then by all means post them. I think the telephony questions that are on topic will generally be more about systems such as Asterisk but feel free to prove me wrong.
With the caveats that you ask questions in accordance with the FAQ, and bear in mind that specialized questions of that type may only attract tumbleweeds, I'd say go right ahead.
I've seen questions on here about PBX systems (not VOIP) and we even have a PBX tag, so questions about cellular networks (as related to professional systems administration) seem to me to be at least as on topic as questions about that dinosaur technology.