Hi,

Check what it shown in the SMS Message Centre setting in your phone.

To check the setting in your phone tap on Messages > more options > settings and locate the option for Message Centre. Tap to enter to change the information.

As each mobile phone service provider has a different setting (it is usually a phone number or a code number) you will need find what is the correct information that has to be inserted by going to your service provider's website and searching for SMS Message Centre.