Is there a customer service phone number? AT&T Customer Service Phone Number 1-800-288-2747. AT&T is a communications giant that is the largest provider of mobile phone service and home phone service.What is the comcast customer service phone number? The main Comcast customer service phone number is: 1-800-XFINITY (1-800-934-6489).Is there a customer service telephone number for? General Customer Service: 1-877-383-4802. For faster customer service, please use the links above to contact the appropriate customer service center for your specific needs.