I was one of the people on the first page to have this issue. Here's some information to help everyone out.
iPhone 4s ported from Sprint
DESCRIPTION OF PROBLEM-------------------
Cannot send out SMS (that's it), cannot send or reply to text to a single person.
I can send and reply to every message you can imagine (iMessage, MMS group messages, MMS picture messages, emails) except SMS. Recieving messages was not a problem either.
NOTE: There are no outages confirmed in my area. For a quick response to check if there's an outage in your area, message VirginMobile USA on facebook. A reply is usually received with in a few hours on the same day.
TEMPORARY FIX--------------
Before the fix, what I was doing was sending group messages to a single person. How?... I would send a text to myself and one other person. This way it would be a MMS/group message. The other person would receive the message, and I would too. Another thing I did was use iMessage with other iphone users, and I used BeeJive GT app for android phone users that use gtalk (google talk, their version of iMessage).
------------------------------------------------ I called Virgin Mobile and this is how it went
CSR--- blah blah blah blah ##update#... on and off reset transfered to tech support...
TECH SUPPORT--- on and off reset, she reset my "messaging service". she is literally reading instructions, and doesn't know what the real issue is. These tech. supports just run through a list. After I explained the situation, they still insist on the options they have. Be patient. I decided not to talk them out of it, I merely waited until her options were exhausted. She said my account was not ported over correctly. I didn't really need to explain anything, and was transfered to someone who has more "tools" to fix this for me. transfered to tech support level 2...
TECH SUPPORT LVL 2--- this tech pretty much did the same thing. doesn't really seem to know, just reads instructions and repeats it. I questioned if it was even the next up tech support level. She told me she's a tech support in the "porting department". It's all the same department just another tech support. After she exhausted her options with the on and off "messaging service reset" she tried to give me a troubleshooting ticket and disconnect the call. She said there's nothing she can do, and they have no other options or work arounds. At this point, I explained that I was apart of this community apple support thread, and a those like ct1g3r were able to get someone to fix it. She insisted that there's nothing they could do. Told her to not give me a troubleshooting ticket, just transfer me to another tech support. BTW; I highly doubt this was a lvl 2 tech support as she did the same as the one before. She seemed like a Lead or senior tech support
TECH SUPPORT LVL 2 (THE REAL ONE, a tech guy)--- I can tell this was the real level to tech support because he didn't give me any BS. Just what's your number? what's your pin? what's the name on the account? What's the problem? I explained in detail. He said he would review the my network settings, place me on hold for a minute. He seemed to know what the issue was. He didn't have any BS for me to do. He pretty much confirmed it was a network/programming issue. Placed me on hold to brief the next person, a specialist, about the issue. Transfered me and explain the next person was informed of the issue and will take care of it.
SPECIALIST--- This guy first went over what he was briefed on. I confirmed my issue with him. He was very helpful no BS. He explained he reactivated my service in the network. Did the on and off to reconnect/reset phone. Did an SMS test. Sent to my wife and myself. WORKS!!!!!! I asked him what it is he did. He said, he deactivated then reactivated my service manually. I told him that there are others with this issue. He believes this process must be done manually to correct. I asked him if he has came accross this issue before or is it common. He said he doesn't take phone calls, and calls usually don't get that far.
SO...EVERYONE WITH THIS SAME ISSUE. GET A SPECIALIST TO FIX IT, DON'T TAKE A TROUBLESHOOT TICKET OR WHATEVER YOU CALL IT. Get transfered until it's done right.
THANK YOU ct1g3r !!!