Hello all, Everyone has probably experienced this at some point in the past: You pick up your analog phone. Rather than hearing dialtone, you are connected with someone who has just called you. Neither you nor them heard a ring. Maybe it's just me, but it seems these "freak incidents" would occur more frequently years ago, than now. I've now experienced this a couple of times with an * system (TDM400p - quad FXO): A SIP exten dials digits which are answered by a Zap trunk. As soon as Zap answers, the SIP extension is connected with an inbound (PSTN) caller (who was expecting to hear an IVR). My questions are: Who's to blame (telco, tdm card, * config, gremlins)? Is this avoidable? Thanks Ryan
On Tuesday 03 May 2005 11:40 am, Ryan Courtnage wrote:> Hello all, > > Everyone has probably experienced this at some point in the past: > You pick up your analog phone. Rather than hearing dialtone, you are > connected with someone who has just called you. Neither you nor them > heard a ring. > > Maybe it's just me, but it seems these "freak incidents" would occur > more frequently years ago, than now. > > I've now experienced this a couple of times with an * system (TDM400p > - quad FXO): > A SIP exten dials digits which are answered by a Zap trunk. As soon > as Zap answers, the SIP extension is connected with an inbound (PSTN) > caller (who was expecting to hear an IVR). > > My questions are: Who's to blame (telco, tdm card, * config, > gremlins)? Is this avoidable?I dont know who to blame, but we've had the same problem here with our small sales team. The sales team (about once a week) will dial a call on their analog phones (analog cordless phones plugged into a few SPA-2001s) - they press 'talk', dial the #, then immediatly are connected to an incomming call... (I use two TDM quad FXO cards to service 8 incomming lines from Sprint). I havnt been able to track it down, and its not reproducable manually... Anybody have any ideas? -josiah -- Josiah Bryan IT Coordinator Productive Concepts, Inc. jbryan@productiveconcepts.com (765) 964-6009, ext. 224
Eric Wieling aka ManxPower
2005-May-03 09:34 UTC
[Asterisk-Users] Freak incidents, who's to blame?
Ryan Courtnage wrote:> Hello all, > > Everyone has probably experienced this at some point in the past: > You pick up your analog phone. Rather than hearing dialtone, you are > connected with someone who has just called you. Neither you nor them > heard a ring. > > Maybe it's just me, but it seems these "freak incidents" would occur > more frequently years ago, than now. > > I've now experienced this a couple of times with an * system (TDM400p - > quad FXO): > A SIP exten dials digits which are answered by a Zap trunk. As soon as > Zap answers, the SIP extension is connected with an inbound (PSTN) > caller (who was expecting to hear an IVR). > > My questions are: Who's to blame (telco, tdm card, * config, > gremlins)? Is this avoidable?It's called "glare". http://home.intekom.com/scotland/cookbook/146.htm http://www.authorizedcom.com/lines_trunks.asp http://www.beagle-ears.com/lars/engineer/telecom/bizphone.htm http://www.zvon.org/tmRFC/RFC3064/Output/chapter4.html
> Hello all, > > Everyone has probably experienced this at some point in the past: > You pick up your analog phone. Rather than hearing dialtone, you are > connected with someone who has just called you. Neither you nor them > heard a ring.I don't think this is a freak incident at all. It still happens to me with people I call frequently and is easily explainable. you make a call, the telco connects it, and before the ring generator comes into a phase of putting voltage on the line, they pick up the phone. The circuit was connected, it just never got a chance to ring, there is nothing freak about it, just a matter of timing. This same thing could apply to asterisk or any other pbx or telco system since they all use the same basic arrangement of connecting circuits and ringing them. There is no hard and fast rule I know of that says a line must ring at least once before the called station can go off hook. Modems and such can be programmed with this rule, but a person picking up can do so at any random time. An exception would be when there is more than one call path to a phone, and effectively picking up to dial is not the same as picking up to answer an incoming call. Also, this could start happening more, not less as technology progresses since something like camp-on would have higher odds of hitting this situation since it constantly retries the number instead of the randomness at both ends if humans are involved.> > Maybe it's just me, but it seems these "freak incidents" would occur > more frequently years ago, than now. > > I've now experienced this a couple of times with an * system (TDM400p > - quad FXO): > A SIP exten dials digits which are answered by a Zap trunk. As soon > as Zap answers, the SIP extension is connected with an inbound (PSTN) > caller (who was expecting to hear an IVR). > > My questions are: Who's to blame (telco, tdm card, * config, > gremlins)? Is this avoidable? > > Thanks > Ryan > > _______________________________________________ > Asterisk-Users mailing list > Asterisk-Users@lists.digium.com > http://lists.digium.com/mailman/listinfo/asterisk-users > To UNSUBSCRIBE or update options visit: > http://lists.digium.com/mailman/listinfo/asterisk-users > > !DSPAM:4277a74f32083462913418! > >Jon Pounder _/_/_/ _/ _/ _/ _/_/_/ _/ _/ _/_/_/_/ _/ _/_/ _/ _/ _/ _/_/ _/ _/_/ _/ _/ _/_/ _/ _/ _/ _/_/ _/ _/_/_/ _/ _/ _/_/_/_/ _/_/_/ _/ _/ _/_/_/_/ Inline Internet Systems Inc. Thorold, Ontario, Canada Tools to Power Your e-Business Solutions www.inline.net www.ihtml.com www.ihtmlmerchant.com www.opayc.com
> -----Original Message----- > From: Ryan Courtnage [mailto:ryan-lists@voxbox.ca] > Sent: Tuesday, May 03, 2005 8:41 AM > To: Asterisk Users Mailing List - Non-Commercial Discussion > Subject: [Asterisk-Users] Freak incidents, who's to blame? > > > Hello all, > > Everyone has probably experienced this at some point in the past: > You pick up your analog phone. Rather than hearing dialtone, > you are connected with someone who has just called you. Neither you > nor them heard a ring. >{clip}> My questions are: Who's to blame (telco, tdm card, * config, > gremlins)? Is this avoidable?This is a condition known as 'glare' and is expected behaviour and is actually quite common on busy lines unless a handshaking protocol of some sort is use (such as wink or ground start). Essentially this handshake signals an intent to use the trunk before it's actually seized, thereby preventing both parties from seizing it simultaneously. Google can provide far more detail. Kris Boutilier Information Services Coordinator Sunshine Coast Regional District
On May 3, 2005 11:40 am, Ryan Courtnage wrote:> Everyone has probably experienced this at some point in the past: > You pick up your analog phone. Rather than hearing dialtone, you are > connected with someone who has just called you. Neither you nor them > heard a ring.It's not a freak accident; the switch just routed a call to you the exact moment that you picked up the line. It happens.> My questions are: Who's to blame (telco, tdm card, * config, > gremlins)? Is this avoidable?Avoidable? Not really; it happens. Is it really that much of a problem? Can I ask why? -A.
Ryan Courtnage wrote:> Hello all, > > Everyone has probably experienced this at some point in the past: > You pick up your analog phone. Rather than hearing dialtone, you are > connected with someone who has just called you. Neither you nor them > heard a ring. > > Maybe it's just me, but it seems these "freak incidents" would occur > more frequently years ago, than now. > > I've now experienced this a couple of times with an * system (TDM400p > - quad FXO): > A SIP exten dials digits which are answered by a Zap trunk. As soon > as Zap answers, the SIP extension is connected with an inbound (PSTN) > caller (who was expecting to hear an IVR). > > My questions are: Who's to blame (telco, tdm card, * config, > gremlins)? Is this avoidable? > > Thanks > RyanReally no one is to "blame" This is known as Glare, or a head on ( collision ) Take a basic Telephony course before attempting to become a telecom engineer. Back in the "good old days" a PBX would have analog trunks that were ground start, and tip was open when idle. The PBX would have an interface that knew this, and if it found ground on the tip would move to the next outgoing trunk. Ground was applied to the trunk by the CO BEFORE it was rung. The ring signal would then start whatever sequence in the PBX was necessary to answer the call. I gather that the FXO card doesn't support a ground start trunk at all, being nothing more than a modem given a new lease on life. Something other than a X100 or TDM400 is needed, and analog Ground start trunks from the Telco are called for for proper two way operation. GS trunks are certainly still available in the US and probably elsewhere. If you need enough trunks, perhaps a PRI instead? John Novack
-----Original Message----- From: asterisk-users-bounces@lists.digium.com [mailto:asterisk-users-bounces@lists.digium.com] On Behalf Of Eric Wieling aka ManxPower Sent: Tuesday, May 03, 2005 12:34 PM To: Asterisk Users Mailing List - Non-Commercial Discussion Subject: Re: [Asterisk-Users] Freak incidents, who's to blame? Ryan Courtnage wrote:> Hello all, > > Everyone has probably experienced this at some point in the past: > You pick up your analog phone. Rather than hearing dialtone, you are> connected with someone who has just called you. Neither you nor them> heard a ring. > > Maybe it's just me, but it seems these "freak incidents" would occur > more frequently years ago, than now. > > I've now experienced this a couple of times with an * system (TDM400p-> quad FXO): > A SIP exten dials digits which are answered by a Zap trunk. As soonas> Zap answers, the SIP extension is connected with an inbound (PSTN) > caller (who was expecting to hear an IVR). > > My questions are: Who's to blame (telco, tdm card, * config, > gremlins)? Is this avoidable?It's called "glare". All elaborate on 'GLARE' Think about opening your front door on your way out just before the person gets a chance to ring the doorbell. Bam, there you are just "GLARING" at on e another. Glare could probably be reduced if you ALWAYS walked out the back door and those coming to visit you go to the front. You can set * to select lines in an order opesite than the way they roll over. For example our lines ring in ascending order line 1, then 2, 3,4,5, etc. If you set the PBX to grab line in decending order you will make outgoing calls on lines 5,4,3,2,1, decreasing the chances that * will open a ZAP door and find someone 'standing' there.... Hope this helps.
Ryan Courtnage wrote:> On 3-May-05, at 10:34 AM, Eric Wieling aka ManxPower wrote: >> It's called "glare". > > Thank you, I'm now walking down the right path. > > From what I've read, glare is common in 2-way loopstart (kewlstart) > circuits, and is impossible(?) to eliminate completely. But now I'm > wondering what Nortel would tell a customer who experiences glare on > their new Meridian system... they must do something to prevent glare > from happening. Any ideas?Yup. Order your lines groundstart.