Purchased an unlocked phone but will it stay that way?

[Midak]

I bought a:
Nokia 3100
V 05.01
15-11-04
RH-50
On the carboard box it came in, one of the tabs said "ver 1.0 09/03"
(I hope that helps)

Anyway, I bought this to use when I go to Irealnd but I wanted to know if I used it in the U.S. with my AT&T SIM, which is now controlled by Cingular, will it lock to AT&T/Cingular? How can I tell if it is locked or not before I go to Ireland?

I checked out that Calculator but I do not know which code to use or what option for the GEN to choose.

Last question :) Does anyone know any online companies that will sell me an o2 prepaid card and ship it to the U.S. so I know I am set before I go?

[Midak]

Thanks for the heads up on meteor. Last time I was there, my Cingular based Sony Ericson picked up on vodafone, o2 and meteor but that was with the Cingular SIM and the cost per minute was about $2.95 so I'm not doing that again. Funny thing was, that phone worked better in Ireland than it did in New York. So, how do I know if it's locked now since I put the AT&T SIM in there?

[Midak]

I do not have a T-Mobil SIM to put in there, nor do I know anyone who does. If it is unlocked, what will happen if I enter an unlock code?