Sony SPP-IM977 - Manual (Page 43)

Telephone Features
43 US
Telephone Features
RINGER OFF
SELECTED
Turning off the ringer of the handset
1
Perform steps 1 to 5 on page 42.
2
Press (0).
You will hear a confirmation beep.
3
Press (OFF).
When “RINGER” is set to “RINGER OFF”
The handset won’t ring. You can still make calls, and also receive
calls if another telephone connected to the same line rings to inform
you on incoming calls.
To turn the ringer on again
Follow the instructions described in “Setting the ringer type” on
page 42.