Why can't Motorola z3 send text messages?

Perhaps the information center has not been established. Go to the SMS folder, find the SMS settings, and then enter the SMS information center settings. The mobile subscriber number is +86 1380 * * * 500. The asterisk is the area code of your location. Unicom users should call customer service to find out what the center number is, and select it as the information center number after setting.