What will happen if I don't pay my termination fee?

So I have an 2 iPhone 6's and an iPhone 5s combined have a total etf of like $1300 and I'm not paying that. I planned to sell the phones to try to pay it off but what if I sell it to an AT&T customer? (Phones came from AT&T) can they just pop their SIM card in and the phone will work since it's locked to att?

You won't be able to cancel your plan

  • When do you pay the upgrade fee for an iPhone? I know it's $36, but aside from the $199 +tax I'm going to pay, do I have to pay the upgrade fee right away or does it show up on my next bill?
  • What happens if you don't pay your carriers monthly fee? I was thinking of buying iPhone 6 but I'm going to shift now so what happens then do I have to pay them the whole money before leaving the country? It's sprint.
  • What happen if I buy an iphone 5 and I don't pay? I mean if I buy the iphone 5 and I make like no call I only play what will happen will they block everything from the phone?
  • Verizon Wireless Termination Fee? I was planning on canceling my plan with verizon wireless. The termination fee is "$175, or $350 if you purchased an Advanced Device". I have two iphones and two regular phones with my plan. Does this mean I have to pay to terminate each phone plan separately or will it be a total of $350 dollars because I own an advanced device?