larry@uunet.uu.net (Larry Lippman) (05/27/91)
In article <telecom11.397.6@eecs.nwu.edu> YSAR1111@vm1.yorku.ca (Rick Broadhead) writes: > I had a similar experience just a few days ago. I dialed a number in > my own area code (416), exchange 392, and was quite surprised to hear > a double ring. This is the first time I have ever heard a double > ring on the calling end. Is it possible that you encountered a "line extender" for FAX and/or modem use, which *immediately* trips the central office ringing and supplies its own ringing signal? Under these circumstances, you may never get a chance to hear the CO ringback tone, with the resultant ringback tone being solely the product of the subscriber's line extender. > [Moderator's Note: I don't know if you meant it the way it came out, > but the telephone instrument has *nothing* to do with the ring you > hear as the caller. What you heard must have been some kind of fluke; > some temporary switch problem. PAT] The above explanation about a line extender notwitstanding, it *is* possible to hear a ringback tone modification cased by the subscriber instrument. In electromechanical CO's, such as SxS, XY and some No. 1 XBAR (if any is still left), ringback tone is usually supplied by capacitive coupling between the called subscriber line while it is being rung and the calling party side of the connector or intraoffice trunk. Some older telephones having electronic ringers may create audible signals on the telephone line due to the design of the ringer oscillator circuit. While such audible signals cannot modify the cadence of the ringback signal, they can provide a decided modification to its sound as heard by the calling party. I first noticed the above many years ago in an Ericophone (remember those?) having a electronic tone ringer. Larry Lippman @ Recognition Research Corp. "Have you hugged your cat today?" VOICE: 716/688-1231 {boulder, rutgers, watmath}!ub!kitty!larry FAX: 716/741-9635 [note: ub=acsu.buffalo.edu] uunet!/ \aerion!larry
Dave Levenson <dave@westmark.westmark.com> (06/02/91)
In article <telecom11.397.6@eecs.nwu.edu> YSAR1111@vm1.yorku.ca (Rick Broadhead) writes: > I had a similar experience just a few days ago. I dialed a number in > my own area code (416), exchange 392, and was quite surprised to hear > a double ring. This is the first time I have ever heard a double > ring on the calling end. It is possible that you reached a DID trunk into a PBX. In this case, the ringing, busy, and other 'call progress' tones are not supplied by the C.O., but by the destination PBX. If this PBX generates a double-ring tone toward the calling party (possibly when it generates a double-ring toward the called party) then that's what you'll hear. Were you calling a commercial establishment? A college dorm or campus? Some other place where you were dialing directly to an extension of a large private network? Dave Levenson Internet: dave@westmark.com Westmark, Inc. UUCP: {uunet | rutgers | att}!westmark!dave Warren, NJ, USA AT&T Mail: !westmark!dave Voice: 908 647 0900 Fax: 908 647 6857
Rick Broadhead <YSAR1111@vm1.yorku.ca> (06/02/91)
In Vol. 11, Issue 413, dave@westmark.westmark.com (Dave Levenson) writes: > Were you calling a commercial establishment? A college dorm or campus? > Some other place where you were dialing directly to an extension of a large > private network? To answer your question: I heard the double-ring when calling the "Management Services" department at Toronto City Hall. Rick Broadhead ysar1111@VM1.YorkU.CA
grayt@uunet.uu.net> (06/04/91)
>> Were you calling a commercial establishment? A college dorm or campus? >> Some other place where you were dialing directly to an extension of a large >> private network? > To answer your question: I heard the double-ring when calling the > "Management Services" department at Toronto City Hall. The double ring will indicate that the destination has answered your call on its own equipment. The real implication of this is that you are now being billed for the time that you are listening to ringing. Tom Gray
John Higdon <john@zygot.ati.com> (06/05/91)
Tom Gray <mitel!Software!grayt@uunet.uu.net> writes: > The double ring will indicate that the destination has answered your > call on its own equipment. The real implication of this is that you > are now being billed for the time that you are listening to ringing. Not generally true. If the reason you are hearing an unusual ringing signal involves a PBX, it is probably a DID connection. Answer supervision occurs when, and only when, the call is picked up by the ringing extension. Busy, no answer, and even local customer intercept recordings do not return supervision on a properly set up PBX. In essence, the PBX becomes the terminating CO. John Higdon | P. O. Box 7648 | +1 408 723 1395 john@zygot.ati.com | San Jose, CA 95150 | M o o !
"John R. Covert 05-Jun-1991 1440" <covert@covert.enet.dec.com> (06/05/91)
>> To answer your question: I heard the double-ring when calling the >> "Management Services" department at Toronto City Hall. > The double ring will indicate that the destination has answered your > call on its own equipment. The real implication of this is that you > are now being billed for the time that you are listening to ringing. Tom, for the Management Services department at Toronto City Hall, this is not the case. As has already been explained, when a PBX has DID trunks, audible ringing tone is returned to the caller directly from the PBX, which can ring any way it pleases. This earlier response was correct, and yours was incorrect. Specifically, 416 392-7715 rings with double ring, but you are not billed until someone answers. I have verified this from a trunk which provides positive indication of answer supervision. john
tom@lynx.aptix.com> (06/06/91)
John Higdon <john@zygot.ati.com> writes: > ... If the reason you are hearing an unusual ringing > signal involves a PBX, it is probably a DID connection. Answer > supervision occurs when, and only when, the call is picked up by the > ringing extension. Busy, no answer, and even local customer intercept > recordings do not return supervision on a properly set up PBX. > In essence, the PBX becomes the terminating CO. It seems there's a potential for fraud here. I assume there are rules for what may be sent out as a local intercept without returning answer supervision. I assume that a call answered by a "we're closed now, call back in the morning" recording ought to be paid for. Are businesses with DID on an honor system in this regard? Tom Ace tom@aptix.com
David E Martin <dem@iexist.att.com> (06/06/91)
In article <telecom11.425.2@eecs.nwu.edu> mitel!Software!grayt@ uunet.uu.net (Tom Gray) writes: > The double ring will indicate that the destination has answered your > call on its own equipment. The real implication of this is that you > are now being billed for the time that you are listening to ringing. Only if the PBX returns answer supervision at that point. PBX's can transfer you all over the place before signaling the calling CO that the call is connected and billing should start. David Martin, AT&T Bell Laboratories, Naperville, IL dem@iexist.att.com, (708) 713-5121
mat@uunet.uu.net (06/08/91)
>>> Were you calling a commercial establishment? A college dorm or campus? >>> Some other place where you were dialing directly to an extension of a large >>> private network? >> To answer your question: I heard the double-ring when calling the >> "Management Services" department at Toronto City Hall. > The double ring will indicate that the destination has answered your > call on its own equipment. The real implication of this is that you > are now being billed for the time that you are listening to ringing. I don't believe so. If it's DID into a PBX, you shouldn't be billed until the PBX indicates that the call has been answered; the PBX can (and must, to be registered with the FCC) generate certain `call progress' tones before giving the electrical indication that the call has been answered (``returning answer supervision''). On the other hand, if you get an ``all of our agents are busy; please hold on'' message, the PBX should have returned answer supervision and you are being charged. (This man's opinions are his own.) From mole-end Mark Terribile
Dave Levenson <dave@westmark.westmark.com> (06/08/91)
In article <telecom11.425.2@eecs.nwu.edu>, mitel!Software!grayt@ uunet.uu.net (Tom Gray) writes: > The double ring will indicate that the destination has answered your > call on its own equipment. The real implication of this is that you > are now being billed for the time that you are listening to ringing. This could be true, but may not be. If a DID PBX is generating the double-ring tone, it probably has not sent off-hook supervision. (There may be some other customer-provided-equipment that does go off-hook and then send ring tone.) Dave Levenson Internet: dave@westmark.com Westmark, Inc. UUCP: {uunet | rutgers | att}!westmark!dave Warren, NJ, USA AT&T Mail: !westmark!dave Voice: 908 647 0900 Fax: 908 647 6857
John Higdon <john@zygot.ati.com> (06/09/91)
Tom Ace <crux!tom@lynx.aptix.com> writes: > It seems there's a potential for fraud here. I assume there are rules > for what may be sent out as a local intercept without returning answer > supervision. I assume that a call answered by a "we're closed now, > call back in the morning" recording ought to be paid for. Are > businesses with DID on an honor system in this regard? Yes and no. There is a potential for fraud, but businesses that have DID circuits maintain a fairly high visibility with the serving telcos. I have known some people who have done some pretty rude things with DID, but eventually someone from telco (or in one case AT&T) discovered what was going on and "suggested some changes" in the way supervision was returned. For example, 800 EAT SH*T used to terminate on a DID that had a barker for a 900 service where you could gripe about bad drivers. The clever person delivered the barker message without benefit of supervision so HE was not charged for the 800 call. When AT&T finally got wind of this, they threated and huffed and puffed, but the person explained that the recording on the 800 number was simply a "referral" to the 900 number. AT&T was not amused, but in lieu of other action disconnected the 800 number and gave it an unembellished referral to the 900 number. Interesting while it lasted. As far as "we're closed now, call back in the morning" is concerned, many businesses do this and get away with it. By the way, do not bother to write me for a list; I still have to live here :-) John Higdon | P. O. Box 7648 | +1 408 723 1395 john@zygot.ati.com | San Jose, CA 95150 | M o o !
macy@fmsys.uucp (Macy Hallock) (06/09/91)
In article <telecom11.425.2@eecs.nwu.edu> is written: >>> Were you calling a commercial establishment? A college dorm or >>> campus? Some other place where you were dialing directly to an >>> extension of a large private network? >> To answer your question: I heard the double-ring when calling the >> "Management Services" department at Toronto City Hall. > The double ring will indicate that the destination has answered your > call on its own equipment. The real implication of this is that you > are now being billed for the time that you are listening to ringing. What? This sounds incorrect to me. My 20+ years (am I _that_ old?) tells me that: DID trunks provide answer supervision to the telco office. That means billing does not occur until answer supervision is provided to the telco by the PBX. All PBX software I have seen for DID trunks works just this way: no supervision until a call is terminated/answered at a station. Rings and busies (and usually recorded intercepts) do not give answer supervision. Just like The Phone Company (tm) ... and this is done to their specification, too. And the FCC and CRTC agree, too. Perhaps you are thinking of some pager terminals or old style IMTS/MTS equipment that used DID trunks in a different way. Macy M. Hallock, Jr. N8OBG 216-725-4764 Home macy@fmsystm.UUCP macy@NCoast.ORG Note: macy@ncoast.org is best reply path to me. uunet!aablue!fmsystm!macy [No disclaimer, but I have no real idea what I'm saying or why I'm telling you]
KATH MULLHOLAND <K_MULLHOLAND@unhh.unh.edu> (06/10/91)
I think Tom Gray was right when he said if a PBX gives you a double ring you're paying for the call. I've asked three telecom CO people this question and all agreed -- the last CO through which the call passed passes the ringing tone. That is true even on DID connections. If you get a double ring from a PBX it is because the PBX returned answer supervision and is supplying its own ring. Yes, when you hear the phone ring, it rings twice, but we all know the ringing the caller hears is unrelated to the ringing the phone creates, don't we? :-} As I understand it, there are a few reasons you can get double ring from a phone company CO. 1) a party line of more than two parties. 2) a step office will supply a variety of wierd ringing and other tones. There may be others, as well. This is all second-hand, but what was coming in these messages didn't agree with my understanding of how our PBX related to TPC, so I started asking questions. Kath Mullholand UNH, Durham NH
"John R. Covert 11-Jun-1991 1710" <covert@covert.enet.dec.com> (06/11/91)
> I think Tom Gray was right when he said if a PBX gives you a double > ring you're paying for the call. He's wrong, at least in the case of 416 392-7715 and most other cases. > I've asked three telecom CO people this question and all agreed -- the > last CO through which the call passed passes the ringing tone. That > is true even on DID connections. If you get a double ring from a PBX > it is because the PBX returned answer supervision and is supplying its > own ring. Kath, you're simply wrong. I happen to be an expert on DID trunks and PBXs. I either know more than the CO people you talked to, or you did not ask the right questions or understand their answers. DID trunks work as follows: CO seizes the trunk and sends digits to PBX. CO cuts voice path through to PBX. What the caller hears from now on, ring, busy, or recording, comes directly from the PBX. At some point, the PBX may or may not return answer supervision. Until the PBX does so, the call is free, regardless of what sounds come out of the PBX. For this reason, AT&T, on long distance circuits, does not cut a FORWARD voice path through until answer supervision is returned. It's pretty simple. If the CO were providing ring, busy, recordings, etc., you would have to have a protocol from the PBX to the C.O. that told the C.O. whether to send a ring or a busy signal. And there would be no way that you could get no charge recordings provided by the PBX that tell you that an extension isn't valid and give you the main number. There is no such protocol in use on DID trunks. The ONLY information a DID trunk can send to the C.O. is answer supervision. There is no way for a DID trunk to tell the C.O. to provide ringing tone or busy or other responses once the digits have been sent to the PBX. As I said in an earlier reply, I called 416 392-7715 and received a double ring. I did this from a line which provides a positive indication of answer supervision. There was a double ring, and there was no answer supervision. If you choose not to believe the experts, there's not much more I can say. john
hildum@ariel (Eric Hildum) (06/17/91)
In article <telecom11.427.3@eecs.nwu.edu> covert@covert.enet.dec.com (John R. Covert 05-Jun-1991 1440) writes: > Specifically, 416 392-7715 rings with double ring, but you are not > billed until someone answers. I have verified this from a trunk which > provides positive indication of answer supervision. Soon, this will no longer neccesarily be true (at least in the USA.) According to recent changes to FCC Part 68.314(h), when a DID call is forwarded out of the receiving switch, answer supervision will generally be returned after about 15-20 seconds (final value yet to be determined), regardless of the actual state of the call. This change was made at the request of the service providers; they felt that they were losing significant sums of money delivering DID calls to PBXes which, due to misprogramming or forwarding of calls over nonsupervisory trunks (eg, out to the public network again), did not return answer supervison when the call was actually answered. The upshot of it all is that you will no longer be able to tell from the call progress tones what the billing status of the call actually is. Eric Hildum Standard disclaimer here (I really don't know what I'm talking about)
bruce@pixar.com (06/23/91)
In a PBX with DID trunks, what happens if something breaks and the PBX never does return supervision? Does a two-way audio path exist? Will the connection stay up as long as desired, or time out? Bruce Perens
tep@ucsd.edu> (06/25/91)
In article <telecom11.427.3@eecs.nwu.edu> covert@covert.enet.dec.com (John R. Covert 05-Jun-1991 1440) writes: > Specifically, 416 392-7715 rings with double ring, but you are not > billed until someone answers. I have verified this from a trunk which > provides positive indication of answer supervision. What kind of trunk provides "positive indication of answer supervision"? Is this a test function in the CO, or can you get at this through a porperly-featured PBX? Tom Perrine (tep) |Internet: tep@tots.Logicon.COM |Voice: +1 619 597 7221 Logicon - T&TSD | UUCP: sun!suntan!tots!tep | or : +1 619 455 1330 P.O. Box 85158 |GENIE: T.PERRINE | FAX: +1 619 552 0729 San Diego CA 92138