Sony SPP-SS961 - Manual (Page 29)

Using "Caller ID with call waiting
service
n
This telephone is compatible with the "Caller ID with call waiting"
service. Make sure that your telephone company offers this service.
Like the basic Caller ID service, you need to subscribe to "Caller ID
with call waiting" in order to use this service.
Even though you may have already subscribed to "Caller ID" and
"call waiting" as two separate services, you need to request a
subscription to "Caller ID with call waiting" as a single service.
This is a new service that combines the two services.
Even though you now have a "Caller ID with call waiting"
compatible phone, unless you subscribe to the combined "Caller ID
with call waiting" service, you will not be able to see the name
and number of the second caller.
When a new call comes in while you are talking, the caller's name
and/or phone number of the new call appears on the display for about
20 seconds.
To switch to another caller
1
To switch to the new caller,
press
( CALL WAITING/FLASH ).
To switch back to the first caller,
press (
CALL WAITING/FLAShD
again.
30
^'
Caller ID Features