You may want to check with another T-Mo rep and act like you have not called before. Different reps have different levels of knowledge. The SIM card may not be an issue and the first rep simply gave you the "form" generic answer or did not know what he or she was talking about.
I have numerous examples where the above technique worked, but I won't go into it.
Call their tech support too, they may be able to answer technical answers about the SIM care/Hawaii.
I can't imagine why the SIM card would be an issue. One can buy new cards for $5 on eBay and all those do is get the phone to operate with the particular carrier.
Maybe the numbers cannot be transferred from there inasmuch as transferring numbers from one carrier to another assumes one is remaining in the same calling area.
But, can you get a T-Mo plan for her, in Hawaii and use it in the continental U.S. without extra charge, e.g., a nationwide plan?
