Unable to send sms

[teo21]

Hi,
 I'm using Sony Xperia tipo dual ST21i2 for nine months with no problems.Before a week an update message appear and in the meantime till i got the update i could not sent sms,every time i tried to i got an emoticon in the side of the message and a message from the device that tell me that the sending was not possible.I update my device today but i still cant send a message although i can receive message,calls and make calls.Could anyone help me please?

[Alexander1]

First of all I suggest that you check with your network operator that your SMS center number is correct. You'll find the SMS center number under messaging > menu button > settings. 

If the SMS center is correct I suggest that you try with another SIM card in your phone.