I just reflowed the GSM chips again after getting a weird problem from it:

-Call a friend, 1-2-3 mins pass, he can't hear me, he disconnects, and I get Network error, the signal disappears completely and after about 1 second everything works just fine and I can talk up to 1h without any problems.

This just happened today after the first reflow, but after that error, I could call and be called without problems.

Got home, made the second reflow, finish the process, put it all back together, and called the same friend, call connected, he answers, he said he couldn't hear me, disconnects, signal went missing for half a second, then he calls me, everything went back to normal. Talked with him about 10 mins after he called me, then I call him and talked for 10 more mins, no more problems.

Can this be a software issue? What could be the problem...?