Also, what is the Nortel old-school system's solution to this. Is it a similar min message length?
-- Nabeel Jafferali X2 Networks -----Original Message----- From: Jim Van Meggelen [mailto:[email protected]] Sent: February-09-09 11:49 PM To: Nabeel Jafferali Cc: [email protected] Subject: Re: [on-asterisk] Audiocodes - Disconnect Supervision Waaaay back in the early 90s when voicemail was not yet ubiquitous, far-end disconnect supervision for loop start analog lines was something that didn't really exist. They were lines, not trunks (the CRTC acually tariffed PBXs and Key Systems differently, as well as the kind of circuits you could connect to them). It was never a problem before voicemail, because as long as your phone system hung up the line (which is what would happen when you hung up your phone), the circuit went on-hook at your end, and the call was terminated correctly. If you wanted far-end disconnect supervision, you had to get a ground-start trunk. These were analog circuits that didn't use a loop to request dial tone, but instead used a ground (we had an extra wire in our butt sets so we could ground the line to the frame to get dial tone when we were testing. As voicemail systems became more common, far-end disconnect supervision on small key systems became a problem. Lines would appear to be hung, but in reality what was happening was that the voicemail simply didn't have the smarts to realize the far end was disconnected, and so it wouldn't hang up the call. The solution was a hack. Carriers began to implement disconnect schemes on analogue lines. They would send a signal of some sort to indicate to the system that the far end had disconnected. This was never perfect, and still isn't (although it's pretty darn good). So the problem is not only related to Asterisk. Any voicemail system on a loop-start analog system has to take into account the facts that a) the disconnect will not come immediately, and b) sometimes it will not com at all. I don't think that there will ever be a way to solve this problem 100% of the time, but you can get close. The first thing to set correctly is the silence threshold. Three seconds is too short, ten seconds too long. What seems to work is about 5 seconds. maxsilence=5 The next thing to figure out is if we end a recording after 5 seconds of silence, we will set our minimum message length to 6, which is one second higher than the silence. This will ensure that any message that is a result of the caller hanging up and not leaving a message, will always be 5 seconds (because that's the silence threshold), and thus will not be a valid message (because it is not the minimum of 6 seconds). minmessage=6 You will have to tell your clients that any messages less than 6 seconds may be treated as a hangup by the system. They might not like it, but I've never seen anybody unable to get over it. If you really want to play it safe, you should put something in your dialplan to set the absolute maximum length of a call. That could even be a few hours if your clients talk on the phone for a while, but at least that way the call will always disconnect eventually. The simple fact is, if you want reliable, fast, far-end disconnect supervision, you cannot use analogue circuits. Jim Nabeel Jafferali wrote: > Thanks for the info. > > Yes, I do get that, meaning the call does hang up 10-11 seconds after the > remote party hangs up. This also means Asterisk voicemail gives me 10 second > blank messages if the call had ended up in voicemail. > > Any way around that? > > -- > Nabeel Jafferali > X2 Networks > > > -----Original Message----- > From: Jim Van Meggelen [mailto:[email protected]] > Sent: February-09-09 5:53 PM > To: Nabeel Jafferali > Cc: [email protected] > Subject: Re: [on-asterisk] Audiocodes - Disconnect Supervision > > You have to wait for the far-end disconnect from the carrier. If you > have a butt set you can monitor the line and listen for it. I have found > it usually takes about 11 seconds to get the signal. > > Nabeel Jafferali wrote: > >> I have an Audiocodes MP-118FXO in production. When a call is made and the >> remote party hangs up, the Audiocodes hangs up the call immediately. But if >> a call is received and the remote party hangs up, the Audiocodes does not >> hang up immediately. >> >> Anyone experienced this issue with Audiocodes or any other gateway in >> general? Any tips? >> >> -- >> Nabeel Jafferali >> X2 Networks >> >> >> >> > > > -- -- Jim Van Meggelen [email protected] http://www.oreillynet.com/pub/au/2177 "A child is the ultimate startup, and I have three. This makes me rich." Guy Kawasaki -- --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
