AT&T 410 820 - Manual (Page 10)

SPEAKER
Speaker lets you listen to a call without lifting the handset. To
speak, however, you need to use the handset or the optional
Hands-Free Unit (page 21).
On-Hook Dialing
Touch Speaker and dial. When the other person answers, lift
the handset.
Speaker
+
Monitor-on-Hold
If someone puts you on hold, touch Speaker and hangup. When
the other person talks to you again, lift the handset to resume
the conversation.
Speaker +
Group Listening
If you want others in the room to hear your conversation, touch
Speaker and continue using the handset.
Speaker
9