RCA Phone Cable Rj11 Telephone Cable in the Voice & Data Connectors department at Lowes.com
Amazon.com: RJ45 to RJ11 Cable, 6 Feet Phone Jack to Ethernet Adapter RJ11 6P4C Male to RJ45 8P8C Male Connector Plug Cord for Landline Telephone : Electronics
Newhouse Hardware 15 ft. Telephone Extension Cord, with RJ11 (6P4C) Connectors, Works w/Telephones, Fax Machines, Modems, Black (5-Pack) MLC15-BK-05 - The Home Depot