Hello,
I am currently using a Sony Ericson Equinox from ~2008, and recently received a newer Samsung Gravity Smart from a family member on the same plan after she upgraded to a newer phone. I've discovered that the simcard from the Equinox (the one synced to my line) is too old to work in the Gravity, however the Gravity still has its old simcard, which AFAIK is not currently synced to any lines (the family member got a new card for her phone).
So my question is, how would I go about transferring my line from the older Equinox's card to the newer Gravity's card, or is this even possible without the original packaging for it? If this isn't possible how much would it be for a new working simcard from T-Mobile?