US Sim card in Puerto Rico?
 

Our first point of entry to the USA is going to be SJU. After a couple days we are going to mainland USA and will need a USA Sim card for my iPhone 5s. I am not so worried about data because there should be wifi everywhere we need it. We do need a phone number while we are there. I see that T-Mobile has coverage in Puerto Rico but I wasn't sure if their Sim cards are the same you would get in the USA?

Where is the best place to get a Sim card (nano) in Puerto Rico? We will need it for 1 week.

A Tmobile sim should work fine in the mainland and PR.

Where would I get one in San Juan? Would 7-11's have them? Or supermarkets?

I'm not sure on PR. In the mainland, a Tmobile store. On Tmo's site for San Juan, they list Walmart and a Tmobile store.