IPhone 4 gets Service then No Service?

Ok so I have an iPhone 4 factory unlocked then when i put my prepaid T-Mobile sim card in, it doesn't work. Sometimes it works then sometimes it just does not work at all, what is wrong with my iPhone, thank you.

Your blocking the signal with the left palm of your hand, on the bottom left of the iPhone you can see a little slit if you put your hand there it will disconnect its a stupid mistake by apple

  • New iPhone won't get service but my older iPhone gets service? I just got a 6s and went to the Verizon store to get my upgrade. I used to have a 5s. My 5s is still getting service and my 6s is not. I turned off cellular data on my 5s and and made sure both data and LTE were working on my 6s but it still isn't working.
  • My iphone 4 never gets service? My iPhone 4 never gets any service anywhere, sometimes it might pick up 2-3 bars outside but then it goes away instantly, i never get it in my house and my area has good coverage, i've tried new microsim, resetting the phone, hard resets, airplane mode on/off, nothing works, i think it might be the aerial that is faulty but i don't know, help would be much appreciated.
  • My Eyes Gets Tired Whenever I Use iPhone I don't know why but recently when I use iPhone, my eyes become really tired. It wasn't like this before. Even when I watch tv. It's not like I'm using iPhone for a long time since this started happening. What should I do?
  • IPhone screen shows Apple icon then shuts off, then repeats I was updating my software on the iphone when the power went off, then the screen went black and showed the apple icon, then it shus off again, then it shows the apple icon. I plugged it into the computer but they computer does not recogniz it so I can't restore it. What do I do?