Take your phone into a repair store for a reception test and leave it for a few hours. If possible, give them the #s and carriers of friends that you aren't receiving messages from. They won't call or bother them, but tech support can use that info to check things.

I'm not sure if they have phones from other carriers or if they have systems that replicate it, but they'll send messages that originate on the other carrier's system to see if gets to your phone.

The phone's reception might have issues, the account might have a block, the local area might have issues. It's just something they start by checking the phone then go from there.

Now when you say Sprint, is it Nextel or Sprint?

If Nextel, may need to have S/N refreshed through tech support, or replace Sim card.

If Sprint, call tech support to refresh device to network.

I have heard that Verizon has issues sending to both Sprint or Nextel, and it's usually only Verizon that I've seen the issue with Sprint phones. I've never have had the issue myself, and it's weird whenever I hear it.

It could be a signal issue only if text were not coming in through every carrier.

-Drake