eli@pws.bull.com (Steve Elias) (10/01/90)
What do LD carriers do when they dial a number that the destination CO has programmed as a "call forward - no answer", and the number forwarded to is busy? In this situation, the caller hears a few rings, and then a busy signal. Surely this will confuse people who call me and don't know that I'm a telecom weirdo... But what about the "supervision" return codes to the originating CO? If someone calls long distance and this happens, will they get billed because of the change in cadence from ringing to busy? eli
john@bovine.ati.com (John Higdon) (10/03/90)
On Oct 2 at 2:40, Steve Elias <eli@pws.bull.com> writes: > What do LD carriers do when they dial a number that the destination CO > has programmed as a "call forward - no answer", and the number > forwarded to is busy? In this situation, the caller hears a few > rings, and then a busy signal. Surely this will confuse people who > call me and don't know that I'm a telecom weirdo... But what about > the "supervision" return codes to the originating CO? If someone > calls long distance and this happens, will they get billed because of > the change in cadence from ringing to busy? Steve, as a telecom weirdo (TM), you must be aware that long distance companies (including Sprint) use the traditional supervisory signal that is not related in any way to what is happening on the audio path. When the distant phone is actually answered, the distant CO notifies the originated CO ALL THE WAY through the IXC (if one is used) via positive means that depends not on any sound made at the distant end. In the old days, this was represented by a reversal of battery on the line or inter-office trunk. In the days of long distance MF signaling, removal of 2600 Hz indicated supervision or "reversal". Now, of course, supervision in indicated through the CCIS control channel. Those two-bit LD companies that still "guess" at supervision generally use a simple timeout -- if the customer stays on the line for more than a preset limit, then supervision is assumed. I'm aware of none that actually "listen" for an answer. Actually, that would be superior to a timeout. In the case of COCOTs (that DO listen for stuff on the line), this would probably not confuse them. Most "listening" COCOTs check for the asymetrical signature of the human voice. A mixture of ringing and busy (both pre-supervision sounds) would probably not result in your coin being collected. John Higdon | P. O. Box 7648 | +1 408 723 1395 john@bovine.ati.com | San Jose, CA 95150 | M o o !
kabra437@pallas.athenanet.com (Ken Abrams) (10/04/90)
In article <12907@accuvax.nwu.edu> eli@pws.bull.com (Steve Elias) writes: >What do LD carriers do when they dial a number that the destination CO >has programmed as a "call forward - no answer", and the number >forwarded to is busy? In this situation, the caller hears a few >rings, and then a busy signal. Are you really sure it works this way? Is a PBX involved? The rule used to be (and STILL should be) that CFDA (call forwarding-don't answer) should only be sent to a number in the SAME SWITCH. The reason for this is the concern you expressed about the confusing progress of the call and the posibility of the supervision getting fouled up as the call is passed to another switch. If the call stays in the same switch, the status of the forwarded-to line is known and the call will NOT progress if that number is busy; the called line will just continue to ring. This in itself is a little confusing since it makes it appear that the call forwarding has stopped working. Having said all that, the situation will likely change with the implementation of CCIS/SS7. When it becomes possible to find the status of the forwarded-to line via an SS7 query, it should then be possible to CFDA outside the office and allow the call to progress only if the line is not busy. Switch boundaries become somewhat blurred with SS7. Ken Abrams uunet!pallas!kabra437 Illinois Bell kabra437@athenanet.com Springfield (voice) 217-753-7965 [Moderator's Note: You might be interested in knowing that your parent company Ameritech offers 'call transfer: busy/no answer' to cellular customers and it is NOT confined to the same CO, same LATA, or even the same area code. *71 on Ameritech cellular is immediate call forwarding; *72 is transfer on busy/no answer. I transfer from my 312 cellular number to my 708 voice mail number in the Centel CO. Cellular One offers the same thing here. On an unanswered call, the caller hears three or four rings, then a few seconds of silence as the call is withdrawn and sent to my voicemail. Then the caller hears the ringing resume again, or a busy signal. On both Cellular One and Ameritech Mobile, the 'if BY/DA' number is programmed each time it is used as desired by the user. Yet when I called Illinois Bell, I was told it was available for my residence phone, but the CO had to program it (all I would do is turn it on/off via *72/*73) and that it had to stay in the same CO. What does Ameritech know they are not telling Illinois Bell? PAT]
jjwcmp@ultb.isc.rit.edu (Jeff Wasilko) (10/04/90)
In Volume 10 : Issue 706, John Higdon wrote about switches 'listening' for an answer rather than using a default timeout. Here at RIT, we have a System 85. I had always assumed that it handled call supervision properly. One of the company's tech support department that I deal with has a policy of letting calls ring, until they can take it, so that callers don't have to pay to wait on hold. I spent four or five hours on hold one month, and was really surprised by the bill when it came (most of the calls were short after they finally answered. It turns out, the switch uses a 45 second time out. What a drag. Jeff Wasilko RIT Communcations
brent@uunet.uu.net (Brent Capps) (10/05/90)
In article <12985@accuvax.nwu.edu>, kabra437@pallas.athenanet.com (Ken Abrams) writes: >>[stuff about call transfer feature encountering a busy signal] > Are you really sure it works this way? Is a PBX involved? The rule > used to be (and STILL should be) that CFDA (call forwarding-don't > answer) should only be sent to a number in the SAME SWITCH. The > reason for this is the concern you expressed about the confusing > progress of the call and the posibility of the supervision getting > fouled up as the call is passed to another switch. [Moderator states that Ameritech call transfer is not confined to the same CO, LATA or even area code] When the CF feature is datafilled for a particular line on a Northern PBX/Centrex CO (and this probably holds true for AT&T equipment as well), the craftsperson has the option of blocking the second leg of the call from being extended along a trunk. The reason for this has nothing to do with supervision difficulty. It has to do with preventing Joe Blow from forwarding his work phone at SchmuckCo Industries to Grandma's number in Ulan Bator, then going home and dialling his work number, causing the call to be forwarded to Grandma's number while Joe only gets charged for a local call (SchmuckCo Industries eats the rest of it, because the forwarding party pays for the second leg). The same thing goes for the 3WC feature. Supervision is not 'passed along' to the next switch; instead the CF software on SchmuckCo Industries' PBX or Centrex CO determines that it needs to hold the first leg while originating the second leg to Grandma's number in Ulan Bator. When she answers, both legs of the call are condensed onto a three-port conference bridge. The PBX or Centrex CO continues to monitor the connection for billing purposes; when it sees a disconnect from either party it tears down the call. By the way, international calls can be selectively blocked by 3WC/CF as well. Brent Capps uunet: ...!kentrox!brent Kentrox Ind., Inc. pstn: (503) 643-1681 x325 Portland, OR "insert standard disclaimer here"