[asterisk-users] Sipura SPA-3000 vs Sangoma A200

[Mindaugas Kezys]

Hello,

Ok, few bad words about A200.

Our company is based in Lithuania.

Our company used SPA-3000, but because of echo problems we are not using
them anymore.

Now we are trying our luck with Sangoma A200 but the following problem
occurred on few systems we installed. When calling person hangups the call,
Asterisk (Sangoma) does not notice that and keeps ringing. Call is hangup
only after 8s! That's totally unacceptable in busy call center. Imagine the
agent which picks up the call and hears total silence.

I tried all solutions found in Google. Most of them are on AsteriskGuru
website. That didn't help. ringtimeout=xxxx in zapata.conf drives Asterisk
crazy. Sangoma support (you will find it bellow) acknowledged that they
don't know how to fix it on A200.

Notice/question to Sangoma and others - why cheap SPA-3000 does not have
this problem and more expensive A200 can't solve it?

Can somebody suggets me working FXO alternative?

Regards/Pagarbiai,
Mindaugas Kezys



Sangoma response to this problem
----------------------------------------------


Hi Mindaugas,

Yuan asked me to respond because I have more experience in this.

The way the phone system works is that when the phone is on hook, the line
voltage is about 48V DC. To ring, the voltage increases to about 90v AC.
When the phone or the FXO goes off hook, the line voltage is about 7 volts
for the duration of the call. If the call is cleared at the far end, the
voltage goes back to about 48 volts, and that tells us that the call has
been terminated. On some systems they use a polarity reversal, or a 500ms
drop of carrier current but the principle is the same.

ON a good PSTN system, this change in voltage at the end of the call is
almost instantaneous. In Canada, for instance, it takes over 10 seconds for
the voltage signal to come through. The result is that on our Asterisk PBX
at Sangoma, we have exactly the same problem as you: People call in, and
hang up when they hear that you are not available, and we get messages about
10 seconds long with no audio. It is very annoying.

We certainly would like to find a way around this ourselves. Bell Canada is
not interested in our problems. We have tried using a silence filter to cut
calls, but it happens often that there is a few seconds of silence in a
call. Busydetect works, but the busy tone only comes much later, long after
the 10 seconds has passed.

I have no idea why some telcos have this delay before sending the disconnect
signal. You may have better luck with your telco than we have had with ours.

Please let me know if you find anything that helps.

Regards,

David Mandelstam
Sangoma Technologies Corporation
email:     dm at sangoma.com
web:       www.sangoma.com
Tel:       905-474-1990 x 106
           800-388-2475 x 106
FAX:       905-474-9223