> > 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...
>From the description, it almost sounds like "glare". With analog fxo lines, that essentially means that both asterisk and the telco central office attempted to use the same pstn line for outgoing and incoming lines at the same time. Statistically, glare will occur more frequently with _small_ numbers of pstn lines and _greater_ amounts of traffic. I'd also guess that part of the problem might relate to how asterisk handles call setup. In other words, when an incoming call arrives at asterisk, asterisk probably doesn't mark the line as busy until after the callerid arrives (and the first internal ring occurs). If an out- going call is initiated at that time, asterisk may not know an incoming call is just arriving. But, that's a guess for sure. Might try using immediate=yes and usecallerid=no to see if that has any impact. If it does, then suspect the above timing issue. _______________________________________________ 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
