traveling with iphone need advice

[psychomom]

Hi, I've joined this forum to ask this question, as I don't know anyone else that can help. I bought my iphone 3g from my brother when he upgraded to 3gs. I took my old sim card and put it in iphone, then called Rogers (Canada) and got the iphone data plan. I didn't restore the iphone to its original settings as my brother had a lot of cool apps on it. It works great, except when I'm somewhere there is no reception, then after a while, I get the 'does not recognize sim card, please reconnect to itunes' message'. When I connect the iphone to itunes on my laptop, everything is ok again. My question is, I'm about to travel to Puerto Rico for a holiday, do not want to take my laptop, and am worried that I'll get this message while away, and being unable to connect to itunes, I'll be without my phone for the rest of the trip. Any suggestions? Thanks.