I have an iPhone with AT&T on my own plan with unlimited data and txt plus minutes. My company gave me a Blackberry Bold 9000 which has a Corp unlimted everything plan. Question is they will allow me to use my iPhone and I can put their SIM card in my phone so I own my phone but use their SIM card and they pay the whole bill. Will this work ok because it would be nice to have them pay for it all and then I can cancel my AT&T plan, or should I call AT&T. i thought the SIM cards were interchangable but I was wondering if anyone came across a similar situation.