Iphone5 can't send text messages.

If you can receive or send SMS, it may be caused by the wrong number setting in the SMS center. It is recommended that you use the iPhone's internal commands to edit the SMS center number:

Set SMS center number: dial *5005*7672*+86 SMS center number # with iPhone;

Delete SMS center number: dial ##5005*7672# with iPhone.

Inquire about the set SMS center number: dial *#5005*7672# with iPhone.

When using the internal command, first use the delete command, and then set the SMS center number.