User's Guide
Connection of Modular Cable
Check that a modular cable is connected between the LINE port and the appropriate telephone line. Use LINE port 1 if only one line is operating.
If multiple lines are used, modular cables are required according to the number of lines to be used.
Use the TEL port for connecting a telephone cord. Even if multiple lines are used, connect a telephone cord to TEL port 1. A telephone cord cannot be connected to the TEL port on the additional line side.