TheRider:The main function of different ringtones assigned to callerids is to know which calls NOT to take.
You forgot to add: .. without having to get up and check the Caller ID unit itself.
With AT&T, I have the Complete Choice plan. I can assign different rings to a limited set of numbers. I have a custom ring assigned to my dad's number. So, when he calls, I get a burst ring instead of the standard one. This works with any phone plugged into the line as the ring is controlled by AT&T -- not the phone.
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