Ya you can continue with your old sim card if your old one don't create any problem otherwise go for new one and in that you have to save again whatever you want.

I just upgraded my phone to a Nokia 6126. I had been using a Motorola v60i which was a piece of junk.

When I attempted to use my new phone with the pre-installed SIM card, I got a "Smartchip Registration Failed" message. So I removed the SIM card from my old phone and it seems to work fine in my 6126.

A year or two ago, AT&T kept sending me letters about my SIM card being too old and that I would need to get it replaced. I never got around to doing this.

Questions:
1. Can I continue to use the "old" SIM card in my new phone?
2. How do I transfer all of my phone numbers onto the new card if I have to swap SIM cards?