I have gone thru the forums and done everything suggested to resolve not being able to send or receive sms text messages on my DEFY XT and it is still not working - I have 3 bars of cell signal strength. I did not try to text on my phone when it arrived only after I ported my number over to it so am not sure if it ever worked.
1.) Hard rest the phone
2.) Cleared the cache
3.) Made sure the Mobile network settings and CDMA settings are correct