Originally posted by: Rottie
No you will not lose your number with new sim card but you have to have same kind of phone for the sim card to work and also the address book or contact book will transfer to new phone
That's incorrect, unless by "same kind of phone" you mean it has to support the same technology. Basically GSM which is used by AT&T & T-Mobile as well as Europe and Asia. Sim cards will work regardless of phone model so long as it supports the proper tech.
So for the OP, let's pretend I am on AT&T. I can lose my phone & sim card, get a replacement sim from AT&T but because I did not have insurance to replace my old phone I had to buy a new phone and decided to get a different phone. Once AT&T activates the sim with my account information, I'm good to go with the same number even on the new and different phone. The phone does not matter. It's the sim card and your account that matters.
Phone carriers who use CDMA (Verizon, Sprint) do not use sim cards so you'd have to get your whole phone replaced but you'll still retain your phone number because it's tied to your account. Again, there is nothing requiring you to get the same phone model as your old one in order to retain your old phone number.
If your contract is up and you decide to switch carriers, all you need to do is make sure you let the new cell phone sales agent know that you want to retain your old number. They'll get the proper paperwork done so you keep your old phone number. So if say you were on AT&T now and T-Mobile (or Sprint or Verizon) has a great deal after your contract expires, you can switch and still keep your old number. Just get the proper paperwork done. So don't feel like you need to stay on the same carrier to retain your old number.
It's darned convenient to have a cell phone. One of the problems is with the convenience, some of us forget to write down our contact information in some other form. A lot of times when we get new phone numbers we just enter it on the phone and that's our only copy of the phone number. Hopefully you don't but if you lose your phone it's possible you lose all your saved phone numbers because it's not written anywhere else. BACK UP YOUR PHONEBOOK!!