This Telephone Cable standard telephone cord with RJ-11 for use with landline telephones, fax machines, dial-up modems, etc. Universally compatible Telephone Extension Cord Cable with all telephones manufacturers.You can use them as replacements for those IP phones. Include 4 Core Telephone Cable and 8 Core Telephone Cable as well as 2 Core Telephone Cable and 6 Core Telephone Cable. Round Telephone Cable and Flat Telephone Cable as well as Slim Telephone Cable.