At&t iphone transfered to cricket?

I bought an iphone4 from my friend and found out it was an at&t phone and my mom pays for my phone bill and my company is cricket is there a way to get this at&t iphone to cricket i know cricket sells them and if anything ill be willing to trade phones with them or something is there any way to get this at&t iphone transfered to cricket because i just bought it and don't want to buy a new one. So what are my options please help.

If all else fails unlock it and use it on strait talk

if your phone has a sim card than yah you can use it on cricket but i don't think cricket had sim cards

No you can't because Cricket doesn't even use SIM cards. If you had a 4S then maybe because its both GSM/CDMA. Sorry bro