The reason your phone isn't able to connect to a network tells me your phones imie has been blacklisted.Did u buy the fone second hand?If so chances are it's been stolen or someone got it on contract then stopped paying for it and now it's blocked,If you look up a guy in the states called Minnesota mobile guy Anyway for 60dollars he is able to change your imie and ur fone will now work on any carrier.The reason I'm telling u this is cause my S6 was blacklisted and he fixed it for me.I didn't even have to send the fone,All u do is connect it to ur laptop then internet and he does it all in 15 mins,I'm in uk and this guy is 3000 miles away yet he fixed it.Thanks Nathan Minnesota mobile guy