We have a Northern Telecom SL100 switch at our company. Certain
phones (such as Meridian 2616) have a display on which the caller's
name and number are displayed for any incoming or outgoing call.
I have noticed that when we place a call to or receive a call from a
number OUTSIDE of our company, and the phone at that number is also
being served by an SL100 (or DMS100), the distant caller ALSO
sees my name and number, and I see the distant caller's name and
I recently noticed this when a friend of mine at our company called a
hotel which happened to have a DMS100. When the hotel operator
transferred him "anonymously" to certain room, the hotel guest's name
and room number popped up on his display phone! Nice security.
I only barely understand what is going on here and I'd like to
1. I can understand how a distant phone user might get my phone
number, via the standard Caller-ID signaling mechanism. But is the
additional information (the string including my name and my extension)
also transferred to all phones as part of the standard Caller-ID
signalling mechanism, or is this indeed part of some Northern Telecom-
specific protocol that somehow piggybacks its way over the public net?
2. Regardless of the answer to #1, can someone point me to a spec
describing the signals used for Caller-ID (I understand they are
wedged between the first and second ring in a call) ? I'd like
to understand exactly what kind of information is carried by
this protocol and how.
3. If the additional information from #1 is carried in an NT-specific
signal, can someone point me to a spec for the NT-specific signal?
4. Can someone explain exactly what the deal is with Caller-ID and
California? What forms of Caller-ID are allowed and what aren't?
What are the restrictions on calls that are CA-to-CA, CA-to-outside,
and outside-to-CA ? If this is an FAQ item please lead me to the
5. If the additional information from #1 is carried in an NT-specific
signal, is that signal also subject to the same legal constraints in
California as "standard" Caller-ID information?
- Chris Pirazzi