Sony SPP-A946 - Manual (Page 38)

38 US Answering Machine Features
Setting up the answering machine (continued)
When the memory is full
The total recording time of this answering machine is approximately
15 minutes (including the greeting, messages, and memo).
When the remaining recording time becomes less than 30 seconds,
“FL” flashes on the display and the answering machine goes into the
memory full status.
To avoid this erase unnecessary messages (see page 40). You can also
erase the messages from an outside phone (see page 46).