[asterisk-dev] Monitoring of Call Hold

[Chan Kwang Mien]

Does anyone know of a way to monitor Call Hold in Asterisk ? e.g.
when a call is put on hold, Asterisk sends a Notification to the phone
such that one of its buttons starts blinking to denote a Call Hold.

The phone does not send any extensions to Asterisk to put a call on hold.
Hence, I think "hint" cannot be used to monitor Call Hold.
Call Hold is realized through the exchange of sip messages.