Possible bug?

[erzzi6]

I have a jailbroken (purplera1n) iPhone 3GS from ROGERS in Canada.

When I went to the US this weekend I had "No Service" the entire time, although my WiFi worked. My phone is not unlocked.
My brother's phone, which is not jailbroken, had full AT&T service.

How do I fix it?
Is this supposed to happen?

[cpjr]

Is your brothers phone on Rogers too? Or ATT. And do you have roaming turned on.

[erzzi6]

Yes we both are on Rogers.

And yes, we both had data roaming turned on, but then turned it off a couple of hours later to not incur any data charges.

[jack776]

I have the exact same problem, except I jailbroke with redsn0w.

So maybe something is wrong with both of them?

[erzzi6]

Maybe is has to do with the carrier settings?

Does a jailbreak mess with those?