switch sim card from one ATT phone to another?

Hello,

I know ATT uses sim cards that tie's your phone number to what phone its inserted into.

I have a 3gs and also have a older 3g iphone. I noticed I can swap the sim card for each phone and my number will work on each phone.

What I am wondering is, a friend of mine has a cheap slide LG phone from ATT. I know I can put the sim card from that into one of the iphones and it will work. I dont think he has a data plan so as long as he turns off his data feature on the iphone will it work fine on the new phone? Also will ATT get upset if he keeps the phone like that?

I figured he could use it as a glorified ipod with texting and phone and use the data when ever he's connected to wifi.

Any comments would be appreciated.

Thx

Yea,

In all honesty the cheaper 15 dollar plan isnt really that much more so it wouldnt be a big deal. As long as the person made sure to use wifi mostly.