iPhone Sim card to backup phone?

[Schmoe0013]

I know there are several threads out there, but I could not find them at first glance.

I just picked up a iPhone today, with a new AT&T account, so I got the Samsung Sync as a "backup"

I asked the AT&T store people if I could switch out the iPhone sim card, to a different phone, and use it. They said that it might work, but when you put it back in the iPhone, you would have to re-activated it because the sim card gets "screwy" (yes, they said that). Which would result in the 2 year contract getting re-renewed from the day you popped it back in.

So, can anyone confirm/deny/offer advice? It would be "nice" to use this backup phone for situations where I just don't feel like taking my shinny new iPhone :D

Thanks in advance!

[appleii2mac]

There is no problem in moving the iPhone SIM into another AT&T or unlocked phone and then back again. It works just fine. The problem crops up if you take another SIM and put it into your iPhone.

[Schmoe0013]

Thank you!