HIGGINS%FNAL.BITNET@uicvm.uic.edu (Bill Higgins-- Beam Jockey) (10/31/90)
I think many TELECOM Digest postings would become clear to me if I just understood one jargon word. What is meant by "supervision?" Bill Higgins Fermi National Accelerator Laboratory Bitnet: HIGGINS@FNALB.BITNET Internet: HIGGINS@FNAL.FNAL.GOV
floyd@hayes.ims.alaska.edu (Floyd Davidson) (10/31/90)
In article <14174@accuvax.nwu.edu> HIGGINS%FNAL.BITNET@uicvm.uic.edu (Bill Higgins-- Beam Jockey) writes: >I think many TELECOM Digest postings would become clear to me if I >just understood one jargon word. >What is meant by "supervision?" Supervision in it's simplest terms is any control signal that indicates whether your phone is on hook or off hook. When you go off hook the line switcher see's that there is now current on your loop (off hook supervison) ... You dial your friend in Alaska and your toll switch needs to know when the distant end is off hook... That used to be done with a 2600 Hertz tone on the circuit, but now it is sent via a data circuit that is entirely separate from the circuit you talk on. Technically any control signal that indicates the status of one part of a circuit, or piece of equipment, to another is a supervisory signal. But what everyone is always refering to is hookswitch supervison. Floyd L. Davidson floyd@hayes.ims.alaska.edu floydd@chinet.chi.il.us Salcha, AK 99714 connected by paycheck to Alascom, Inc. When *I* speak for them, one of us will be *out* of business in a hurry.
grayt@uunet.uu.net (Tom Gray) (11/01/90)
In article <14174@accuvax.nwu.edu> you write: >I think many TELECOM Digest postings would become clear to me if I >just understood one jargon word. >What is meant by "supervision?" Control information is sent two ways on a telephone loop. Outgoing (ie from telephone to CO/PBX or the originating side of a trunk), its called signalling. Incoming (ie from CO/PBX to telephone or the terminating side of a trunk its called SUPERVISION. There is a special type of supervision called answer supervision, which indocates that the called end has answered and the call is completed and later that the called end has released. Hope this helps - forward and back - siganlling and supervision.
floyd@hayes.ims.alaska.edu (Floyd Davidson) (11/01/90)
In article <14206@accuvax.nwu.edu> Tom Gray <mitel!smithd!grayt@ uunet.uu.net> writes: >>What is meant by "supervision?" >Control information is sent two ways on a telephone loop. Outgoing >(ie from telephone to CO/PBX or the originating side of a trunk), its >called signalling. Incoming (ie from CO/PBX to telephone or the >terminating side of a trunk its called SUPERVISION. There is a special >type of supervision called answer supervision, which indocates that >the called end has answered and the call is completed and later that >the called end has released. >Hope this helps - forward and back - siganlling and supervision. The direction does not make any difference. Supervision is control signaling. Ref: "Notes on the BOC Intra-LATA Networks - 1986", Bell Communications Research. See page G-29. Comment: I liked the title "Notes on the Network", as it used to be known, a lot better. Nicer sound to it... Floyd L. Davidson floyd@hayes.ims.alaska.edu floydd@chinet.chi.il.us Salcha, AK 99714 connected by paycheck to Alascom, Inc. When *I* speak for them, one of us will be *out* of business in a hurry.
cowan@marob.masa.com (John Cowan) (11/02/90)
In article <14174@accuvax.nwu.edu>, HIGGINS%FNAL.BITNET (Bill Higgins-- Beam Jockey) writes: >What is meant by "supervision?" "Supervision" is the signal returned by a remote central office to your local central office to indicate that the call has gone through (the party has answered) and billing for the call should begin. How this is done physically varies from place to place: one common method is to reverse the DC polarity (48 volts) on the phone line. When the called party answers, his central office is said to "return super- vision". The call is also said to "return supervision" or just to "supervise". E.g. "Operator, this payphone took my money even though the call didn't supervise." Problems with supervision occur when the calling party is not just a dumb telephone directly wired to the central office, but is a PBX (private business exchange), COCOT (customer-owned coin-operated telephone) or other device which wants to make its own billing decisions. If the local central office does not forward the supervision information to the PBX or COCOT, it has to guess whether the called party has answered. This is typically done by "timeout"; in other words, if the call is shorter than a certain magic time, assume it didn't go through; otherwise, assume it did (even if the caller just let the callee's phone ring 25 times). Another type of supervision problem arises when an alternative IXC (inter- exchange carrier, i.e. long distance company) fails to get supervisory information from the called party's central office. In this case, the IXC itself has to use the same timeout trick to decide if the call went through. It is not possible to just listen for ring, busy signal, etc. because these tones vary too much from place to place. Hope this helps. cowan@marob.masa.com (aka ...!hombre!marob!cowan)
yazz@prodnet.la.locus.com (Bob Yasi) (11/02/90)
>What is meant by "supervision?"
I know other responses have been posted, but I thought a simple answer
to a simple question would help. Anyone looking for technical
completeness will NOT find it in this post! (:-) You Will understand
supervision tho:
When you call your friend long distance, you shouldn't have to start
paying for the call until your friend actually answers the phone. The
signal (from his end) that tells the billing equipment (at your end)
that your friend picked up the phone is called supervision.
There are lots of situations when supervision is NOT provided, and
these tend to be the subject of discussion, since phone bills get
screwed up as a result. Equipment that doesn't get supervision
generally makes guesses as to when and whether the phone was answered.
Hope this helps.
-- Bob Yazz -- yazz@Locus.com