Bell Vogue running Sprint Rom and Bell radio

[wjt3]

Sorry I'm a newbie at this stuff so bear with me,
I'm a Bell Vogue user with Bell's unlimited data plan, but using the Sprint Rom (OMJ's 6.1) when I go online it connects to a #777 Sprint PCS. I'm scared that Sprint will somehow bill me? is this true or does it just say Sprint, but i'm actually using Bell's network. And if so, is there a way i can rename it? I tried renaming it but it uses a login and password which I'm not sure if i need to get that from Bell.

Thanks