I'm mostly thinking it would be interesting for mobile data competition. Though so many people are tied up in complicated family plans that maybe it doesn't matter much.
If my AT&T 2-year commitment ran out and I could just press a button, put in a code from a card I bought at Wal-Mart, and take T-Mobile for a 1-month test, there'd be more pressure on AT&T to keep their prices sane.
If my AT&T 2-year commitment ran out and I could just press a button, put in a code from a card I bought at Wal-Mart, and take T-Mobile for a 1-month test, there'd be more pressure on AT&T to keep their prices sane.