A light on the phone blinks when I have a voicemail. How?

This is kind of a silly question, but it’s bothered me for days. How exactly does the phone know that there is a message waiting for me? Is there a special signal or voltage sent down the line that signifies this? Does it have something to do with the broken dial tone when there is a message waiting? Are the broken dial tone and this special signal (if it exists) related? I would greatly appreciate the straght dope from any telecom gurus out there.

A good question - my phone does this as well, and I would really like to know the answer myself. Guys?

Does your phone have a “stuttering” dial tone when you have messages? (I guess the first question is: Are you using the phone company for voice mail?)

I use Bellsouth’s voicemail system, and when I have a message waiting, my dial tone ‘stutters’ when I first pick up the phone. My callerID also blinks when I have messages. The way my callerID know I have messages, is because every five minutes or so in internally picks up my phone and ‘listens’ for that stuttering dial tone.

Hope that helps…

Yes, I use the phone company for voicemail and I have a stuttering dial tone when I have messages.

This is what I though it might do–I was just curious because it would seem to be the easiest solution, yet rather inelegant to have to open the phone line every few minutes.