Can my ex get his old iPhone blocked?

My boyfriend and I broke up a few weeks ago and ever since he's been abusive to me online, resulting in him threatening to call EE (his phone network) and getting my iPhone that he gave to me blocked for good. Can he do this? And if so, can I make the phone so it is unblocked without losing all of my stuff on the phone? My phone is an iPhone 4s.

Lesson: don't be completely dependant on a guy

Yes he can block it if he reports it lost or stolen as he is the one who bought it. It is illegal to unblock the phone(changing imei number) but it's only block in that country. I can be used normally in other countries.
You will not lose the stuff on your phone, you will just not be able to make/receive messages and phone calls as you will have no service.
So it can be still be used in the same way as an iPod touch.

As long as the account and contract is under your name, then you have nothing to worry about.