My iphone is messed up and my friend offered to let me use her iphone. She has a 4s, mine is a 4. She says I can use it but I'm not sure if I can. Is it possible to use her iphone on my account?
Can I use a tmobile iPhone on Verizon's network?
No. T-Mobile uses GSM, while Verizon uses CDMA.
No, those two companies use different technology and their phones are not compatible with each other.