System-wide broadcast messages should never light the lamp on the phones for a few reasons: Consider a system with 6 ports and 100 users.
1. You would flood the port/channel that sends MW indication. For integrations requiring that a port go offhook, send DTMF to light the lamp, and go onhook, you're talking 2-3 seconds per lamp. At 100 users, that's 3.5-5 minutes just to light the lamps.
2. If a significant number of people have Notify Me or outcall notification turned on, ports are going to be occupied with outcalling.
3. You could potentially have 100 people trying to retrieve this message at the same time.
So, 6 ports, maybe 1 stuck doing MWI, 2-3 pumping out calls to pagers/cellphones, leaves 2-3 ports to handle a bunch of people trying to check this message all at the same time. You as the system administrator then get called because "voice mail is broken, it's been ringing busy for the last 5 minutes". When in reality, it's just jammed up because everybody in the system got a message at the same time.
