While sending a text message you might encounter a problem that would obstruct you from sending it. You would get error messages like ‘Sending failed‘ or ‘Message not sent‘ etc. The problem is your operators Service Center (SC) number has been altered or changed somehow. This Service Center (SC) number is used to send text messages. Now for the solution to this problem, Google your operators SC and put it in Message Center filed. Message Center is usually located in Settings > Messages > Settings > Message Center. After inserting the correct Service Center number Save the settings.
Now you’ll be able to send text messages.