[Asterisk-Users] One phone ringing, one phone flashing ?

[Stefan-Michael. Guenther (in-put GbR)]

Hi,

well, some clients have strange ideas and wishes (at least to my mind).

Yesterday I gave a presentation about asterisk to a CEO.
At the end he asked me whether asterisk is able to do the following:

When a call for the CEO comes in, the calling number should be shown on the 
display of his phone and the phone of his secretary. The secretary's phones 
should ring, but at his phone only a light should flash.

;-)) No, turning off the sound isn't the solution.
This restriction should e.g. only apply, when it is an external call, internal 
calls should result in ringing both phones.

I'm not quite sure, whether this could be a feature of asterisk or the phone 
or both together.

Does anything of you successfully set up something like this or could 
recommend a phone that would help/support it?

Thanks a lot in advance,

Stefan