Sony PCV-R532DS - Manual (Page 76)

VAIO Digital Studio Reference Manual 68
Modem Connector
The Modem connector on the system board is a 1 x 4-pin header that is
not in use.
Modem
Pin Signal Name
1 Ground
2 Modem Out
3 Ground
4 Phone In
KY0062C.VSD
Modem
1 4