For me it took longer because my AT&T account was under my wife's SSN and I opened the new T-Mobile account using mine. The discrepancy bollixed the automatic process and I had to call T-Mobile customer service to get it done. As I recall, once I talked with customer service it only took an hour or so before I got the "Welcome to T-Mobile" text message and I could dial out on the phone, but for a few hours after that I had to carry both phones because incoming calls still rang my AT&T phone. Everything was all set by the time I got up the next morning, though.