Why can I still send texts to other iPhones even though my iPhone has NO sim card?

My iPhone stopped recieving calls properly so I've had to put my sim card into a different phone. Why when my mate text me from his iPhone did I receive it still on my iPhone and not the phone with the sim card in. And I was able to text him back from the iPhone but when he called me the little Nokia that I'm using rang… I'll be honest, I really don't understand how iOs stuff works…

No way, you must have a SIM card on your phone.

Connect your iphoen to your PC. Download latest itunes software. Perform a full backup of your phone and restore it through itunes. Check these links

http://support.apple.com/.../kb/HT4137

Video on how to backup and restore

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