I cannot send nor receive calls, nor send and receive text messages as of yesterday, April 18, 2011... I am currently using a postpaid SIM... thanks
there are several factors why you are unable to send and receive messages and make outgoing calls and receive incoming calls.
network issue: are you the only one experiencing the problem? try to check with someone who is on the same location and is using the same network as you if he or she is experiencing the same problem as you. if yes, then it may be a problem with your network.
make sure that you have good signal and contact your service provider too and ask them if they have an ongoing maintenance in the area and ask if the sms and calls services are activated on your account
phone issue: if you have a good signal and still can't send, receive text messages, do and receive incoming, outgoing calls, try to do these: call the service provider and ask for the default network pin, then go to the settings of your phone, call settings, call barring, deactivate all barring
try inserting your sim card to another phone and try to send an sms
turn off your phone, remove battery and sim card and then wait for a few seconds, then put back the sim and battery and turn on the phone then try to send an sms