About 36,000 Verizon workers went on strike early Wednesday after the communications company failed to reach an agreement with unions representing workers for its wireline operations.

Verizon has said that consumers will be mostly unaffected because it has trained thousands of nonunion employees since last year to fill in for those who walk the picket line. Union workers counter that the strike will impair Verizon’s ability to deliver quality customer service, including service calls and equipment installations.

Here’s a guide to which consumers may be affected, who won’t and how any disruption might manifest itself.

Which services will be affected?

The unions generally represent workers for Verizon’s wireline operations, which include the company’s landline, high-speed Internet and television services. These services are mostly available only in the Northeast, including Massachusetts, Rhode Island and the region from southern New York to Virginia. Verizon offers home wireline services in parts of nine states, serving about 15 million phone lines. The unionized workers perform a range of tasks, like fixing a phone line that’s out of service, installing new phone and broadband Internet lines, or fielding customer support calls.