Sony PCV-RX791 - Manual (Page 25)

Identifying Components 13
Telephone and Line Jacks
The telephone and line jacks are physically identical and have identical
connections. They are standard RJ-11 female phone jacks. However, the
line jack is for connecting to a telephone line that comes from the wall,
and the telephone jack is for connecting the computer to a telephone.
The modem installed on your computer may differ depending on the
configuration you purchased.
S/P DIF Optical Out Port
The Plastic Optical Fiber (POF) output port for the Sony®/Phillips
Digital Interface (S/P DIF) can be used to connect compatible audio or
video equipment, such as CD/DVD players or MiniDisc recorders.
Line Telephone