If you rather keep your contract phone, i suggest paying the $50, as you will pay monthly for your service even if you don't use the contract phone. Or you can get a new pre-paid cellphone starting at under $50 and let your contract expire. There are many pre-paid providers to choose from...
I tried to send my girlfriend an MMS containing a picture, but my phone flipped out an error saying that there was an error resolving the recipient's address, but i used a phone number, not an address. so i wanted to try the Email method, but i don't know the cellphone Email format and address...