I've seen that complaint on other phones from T-Mobile to iPhones. It's either an issue with AT&T/T-Mobile or with the iPhone itself. It wouldn't surprise me if it were the iPhone's fault, considering every time daylight savings time rolls around, thousands of people don't wake up on time (a glitch they haven't fixed for like three years).
This happened to me as well... I called T-Mobile so many times trying to fix the problem and finally I had to cancel my service. It was out of control. I was getting 6 out of 10 texts or MMS....
Almost everyone texting me had iPhones on AT&T.
T-Mobile was blaming AT&T and AT&T was blaming T-Mobile... Go figure.
To be honest, I miss T-Mobile, if this problem was fixed I'll go back in a heartbeat. Unfortunatelly I cannot afford not to receive my texts, specially from my boss.
I believed is not the phone is the carrier because I work in New York in a building , my phone did not received all the text of my friend which is on the other room. But in NJ where I live I received 100% all my text and calls. Mos of my co worker that live in New York City have AT-T , Sprint seldom to use T-Mobile as their carrier.