[Asterisk-Users] Command to light MWI on 7940 /7960

[Asterisk]

We have several agents on queues, and want to indicate to them that they 
are logged in or logged out. We have tried several different ways, from 
changing the screen to presenting different service menus, but cannot 
get anything to be "in their face" (their words, not mine).

One of our team has suggested, as the agents do not have voicemail, is 
to use the MWI on the 7940 phones to indicate that they are logged in.

Short of dropping a file into the INBOX of the particular extension 
(mucking around with files is yucky) is there any way of achieving this 
with the dialplan ? I was thinking of being able to send a SIP notify 
message "oi, you at 560, light your lamp" or something like that.

Anyone done anything similar ?

Julian