No service or searching, signal problem

So my iphone 4s show me in upper left corner Searching and then No service but in carrier when I set to manual show me list of networks and if I select one then is No service or Searching, this is when I'm at my home, if I go in near city, phone connects to network and i can call when phone is in my hand and have speaker on if i take phone near ears then show me call failed, if i enable 3g in cellular, phone have full signal but can't call or send sms, imidediately show call failed. i tried all the software solutions which were suggested on forums (date&time, reset network, restore, airplane mode) but no luck. So I think there is hardware problem, I read there can be problem in blue coil connector so I gently push it and it fell off, from then phone didn't show me carrier any more, then on one of forums are saying that you can solder there where it was blue coil, so i did this with soldering gun and the phone again show me carrier, but still no service. So there must be something wrong on any other part in phone. like I say in city have in upper left showing full signal sometimes when i get home there is full signal but can't call (call failed). I'm using this sim card in other phones and there works perfectly, I use sim card of friend in iphone 4s and same problem, so there is iphone problem and hardware.

i hope you could help me, or just any suggestion which part in phone is faulty, it is something about antenna, signal.