[Asterisk-Users] UK, Disconnect supervision

[Jonathan Attwood]

Which firmware version are you using on your spa3000?

Peter Hoppe wrote:
|| Hello!
|| 
|| This is actually less a question than some information, if anyone else
|| struggles with the same issue.
|| 
|| I am located in the UK and use a Sipura-3000 adapter to connect to a BT
|| line (via fxo port). One problem I had was that disconnect supervision
|| didn't work:
|| 
|| Some caller phones me (my adapter)
|| adapter goes off-hook (answers call)
|| caller hangs up
|| adapter doesn't realize and stays off hook.
|| 
|| I researched into it and found that the BT exchange delivers a CPC (0.1
|| sec) upon the caller's hangup and a disconnect tone about 3 seconds
|| later. The tone lasts 6 seconds and remains constant during that time.
|| I recorded the disconnect tone with Cool Edit and did a frequency
|| analysis on it and got the following components:
|| 
||     400Hz/-56dB +
||     1200Hz/-69dB +
||     2000Hz/-65dB +
||     2800Hz/-59dB +
||     3600Hz/-59dB
|| 
|| If normalized with -56 dB reference level, I get
|| 
||     400Hz/0dB +
||     1200Hz/-13dB +
||     2000Hz/-9dB +
||     2800Hz/-3dB +
||     3600Hz/-3dB
|| 
|| I suspect that the harmonics (1200, 2000, 2800, 3600)Hz may not have
|| come from the Exchange, but were distortions.
|| 
|| After the 6 seconds the tone stopped and there was succession of two
|| 'clicks' on the line (another CPC? haven't looked into that); both were
|| 0.3 secs apart.
|| 
|| I tried to use both, the CPC and the disconnect tone in the Sipura-3000
|| settings. Unfortunately I couldn't get disconnect supervision via the
|| disconnect tone to work. In a post on the voxilla forum
|| 
|| http://voxilla.com/PNphpBB2-viewtopic-t-2904.html
|| 
|| I found some further info on disconnect tone in the UK - unfortunately
|| I couldn't get those settings to work. I also looked into BT's SIN
|| notes (on http://www.sinet.bt.com , notes 350, 351) but failed to see
|| further information on what tone they exactly deliver for a disconnect
|| event. 
|| 
|| However, the CPC did work. I set the adapter to a CPC minimum time of
|| 0.05 seconds, and from then on it recognized remote disconnection in
|| every test phone call. If I set the time too short I got problems - for
|| incoming calls the adapter started to mistake the incoming ringing for
|| disconnect events and simply wouldn't go off hook anymore.
|| 
|| Now, these are the settings I configured my adapter with:
|| 
|| Settings:
|| spa-3000-setup-web-page/PSTN-line-tab/PSTN-disconnect-detection-section:
|| 
|| 'Detect CPC' => 'yes'
|| 'Min CPC Duration' => '0.05'
|| 
|| I also have
|| 'Detect Disconnect Tone' => 'no' [as it didn't work]
|| 'Disconnect Tone' => '400 at -30,400 at -30;5(5/5/1+2)'
|| 'Detect Polarity Reversal' => 'Yes'
|| 'Detect PSTN Long Silence' => 'yes'
|| 'PSTN Long Silence Duration' => '150'
|| 'Detect VoIP Long Silence' => 'no'
|| 'VoIP Long Silence Duration' => '30'
|| 
|| but the relevant values are 'Detect CPC' => 'yes' and 'Min CPC
|| Duration' => '0.05'
|| 
|| 
|| I hope this helps, if anyone struggles with unrecognized disconnects.
|| 
|| God bless, Peter
|| 
|| 
|| CPC: Calling Party Control: A short break in the line current in the
|| called party's phone line when the calling party hangs up.
|| (def. from http://www.vikingelectronics.com/glossary/telecom-term.php)
|| --
|| dyslexics of the world - untie !
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