There are several Verizon Customer Service phone numbers; it depends on what you need to do.
Customer Service Main Phone Numbers
800-483-1000 - Customer Service (General)
800-483-2000 - Trouble Reporting
800-483-3000 - Billing
800-483-4000 - New Service
800-483-5000 - Small Business
800-483-6000 - Large Business
800-483-8000 - Service Changes
Specialized Services Phone Numbers
800-VERIZON - (800-837-4966) - Verizon General Info / Customer Service / Repair [24 Hours] 888-553-1555 - FiOS Resolution Center ("FRC") - [24 Hours]
800-567-6789 - High Speed Internet (DSL) Tech Support - [24 Hours]
877-461-2284 - Escalations (not normally given to the public unless an issue needs to be escalated).