I’m tired of paying silly cellphone roaming charges when I travel south of the border.

I’m curious about the possibility of getting a US SIM card for my iPhone, and switching my “main” contact number to my GrandCentral number, which will then call various numbers (two cell numbers, landline, possibly softphone).

I used a European pre-paid SIM card last time I was there, and that worked fine, but I’m asking about the GrandCentral bit in particular, as well as any good plans/prepaid cards for the US that work for my episodic usage needs.

Any advice?