[Asterisk-Users] ISDN/CAPI outgoing calls - weirdness with ringing

Michael J. Tubby G8TIC mike.tubby at thorcom.co.uk
Sun Dec 25 01:53:44 MST 2005 

Armin,

Season's Greetings...

See notes below....


> On Sat, 24 Dec 2005, Michael J. Tubby G8TIC wrote:
>> I changed the dial-string to include flags 'ob' as you mentioned (below)
>> and now I get the following when I dial a BT phone number
>>
>> - dial number, get:
>>
>>        Proceeding (in 100) briefly
>>
>> - after a second or so:
>>
>>        Ringng Destination (in 180)
>>
>> - double ringing tone:
>>
>> BT style ringing generated by the exhange
>> Cisco phone US-style ringing (generated by the phone)
>>
>>  these are overlaid on each other (mixed together)
>>
>>
>> My hunch is that there's something not right with the call set up 
>> sequence
>> and CAPI handling.
>
> This is not a problem of CAPI. When you specify 'b' for early-b3, you will
> get the tones from the switch. If your phone adds its own tone, even when 
> it
> receives progress tones, then it is incorrect (maybe wrong setup).
>
> Armin
>


However the difference that I see looking at the Cisco 7960 phone which
shows a version of the SIP messages on its status line is:

    100 Proceeding
    183 Session Progress
    180 Ringng Destination

the order of which varies and depends on the dialled number.

Some dialled numbers go: 100->183->180 and these produce one set
of alerting/ringing correctly.

Some dialled numbers go: 100->183 and stay in state 183 until the called
party answers - these are the ones that produce no ringing.

If I add the 'o' to the existing 'b' flag then dial it appears to change the
behaviour so that the phone goes 100-180 for all calls but some give
me a single (phone generated US style ring) while others give the 'double
ringing'.  The ones that produce double ringing are the ones that would
have rung before, while the ones that now produce ringing (from the
exchange) are the ones that used to be silent.

The ISDN line is 2 x BRI (4 channels) bonded and running in point-to
point mode supplied by British Telecom.  The setup of the ISDN has
not changed and we used to have a Panasonic KXTD-816 PABX on
the line -- all numbers dialled and worked the same when we had the
KXTD.

So my hunch is that there is still an interaction that is different between
ISDN<-->CAPI<-->Asterisk based on the dialled number -- to prove
this I will have to get my copy of Q.931 out [I have one somewhere :o]
and do some protocol traces...


Regards


Mike



>> I'll send you some protocol traces off list.
>>
>> Regards
>>
>>
>> Mike
>>
>>
>>
>>
>> ----- Original Message ----- From: "Armin Schindler" <armin at melware.de>
>> To: "Michael J. Tubby B.Sc (Hons) G8TIC" <mike.tubby at thorcom.co.uk>
>> Cc: "Asterisk Users Mailing List - Non-Commercial Discussion"
>> <asterisk-users at lists.digium.com>
>> Sent: Sunday, December 18, 2005 3:12 PM
>> Subject: Re: [Asterisk-Users] ISDN/CAPI outgoing calls - weirdness with
>> ringing
>>
>>
>> > On Fri, 16 Dec 2005, Michael J. Tubby B.Sc (Hons) G8TIC wrote:
>> > > All,
>> > >
>> > > I have the following set up:
>> > >
>> > > Fedora Core 4 box (yum updated to current)
>> > > Asterisk 1.2.1 + Chan_Capi-cm-0.6.1
>> > > AVM C4 card
>> > > 2 x ISDN2e lines bonded with switchboard number, fax number and 10 x
>> > > DDI
>> > > numbers from British Telecom
>> > > 14 x Cisco 7960 phones with SIP 7.5
>> > >
>> > > The ISDN lines work in P2P mode and calls are presented with the last
>> > > 4 digits
>> > > only - I land them in a context and branch out from there -
>> > > everything to do
>> > > with incoming calls works just fine!
>> > >
>> > > I have a problem with outgoing calls that are routed over the BT
>> > > network and
>> > > the way in which 'ringing' is presented... depending on the called
>> > > party
>> > > number (hence phone provider) I get different results. For example:
>> > >
>> > > a) if I dial another BT number I get a fraction of a second's ring
>> > > followed by
>> > > silence until the called party answers. The Cisco phone displays:
>> > >
>> > > Proceeding (in 100)
>> > >
>> > > very briefly and is almost immediately over-written by:
>> > >
>> > > Session Progress (in 183)
>> > >
>> > > until the called party answers - at no point is Ringing Destination
>> > > (in 180)
>> > > displayed
>> > >
>> > >
>> > > b) if I dial an Orange or O2 mobile number I get a second or two's
>> > > worrth of
>> > > silence [while the Orange network locates the mobile] then the mobile
>> > > rings in
>> > > the normal way and the Cisco phone plays out US style ringing. When
>> > > the number
>> > > is dialled the phone displays:
>> > >
>> > > Proceeding (in 100)
>> > >
>> > > when the mobile starts to ring the Cisco phone displays:
>> > >
>> > > Ringng Destination (in 180)
>> > >
>> > >
>> > > c) if I dial a Bulldog phone number then I get three messages:
>> > >
>> > > Proceeding (in 100)  - for a second or so
>> > > Session Progress (in 183) - for a couple of seconds
>> > > Ringng Destination (in 180) - while the called party's phone rings
>> > >
>> > >
>> > > d) and the really weird one - if I dial *some* international numbers
>> > > I get
>> > > both UK (BT) ringing tone overlaid with Asterisk/VoIP (US) ringing
>> > > tone
>> > >
>> > >
>> > >
>> > > I have two ways of dialling out:
>> > >
>> > > 1. with an explicit "9" for an outside line -- get dialtone from BT
>> > > and then
>> > > dial rest of the digits - like a legacy PBX
>> > >
>> > > 2. dialing just based on the fact that the extension starts with a
>> > > zero so its
>> > > an outside call via BT
>> > >
>> > >
>> > > I have tried all combinations of early B3 connect 'always', 'on
>> > > success' and
>> > > 'never' and it doesn't appear to change things... the relevant part
>> > > of
>> > > extensions.conf is below for completness.
>> > >
>> > > Before I dive in to the next level down:
>> > >
>> > > - is this a known issue?
>> > > - is there a solutiuon/workaround/patch/fix
>> > > - do I need to get down and dirty with CAPI and SIP debug?
>> >
>> > Have you tried CAPI-Dial option 'o' ? Together with 'b' it should give
>> > you progress in any case.
>> >
>> > Armin
>> >
>> > > Mike
>> > >
>> > >
>> > >
>> > >
>> > > ;
>> > > ;  external-routes: this is where we get to dial out
>> > > ;
>> > > [external-routes]
>> > >
>> > > ;
>> > > ;  outgoing via main ISDN line using explicit "9" for an outside
>> > > ;  line
>> > > ;  and ISDN eqarly B3 connect ("overlap sending") to drop us to
>> > > ;  the
>> > > ;  BT provided dialtone and work like a normal/legacy phone
>> > > ;  system -
>> > > ;  we force the caller ID to our exchange number so that DDI's
>> > > ;  dont
>> > > ;  leak out
>> > > ;
>> > > exten => 9,1,NoOp("ISDN: Pickup outside line (early B3 connect) for:
>> > > ${CALLERIDNUM}")
>> > > exten => 9,2,SetCallerId(${THORCOM_MAIN})
>> > > exten => 9,3,Dial(CAPI/g1//b)
>> > > exten => 9,4,Hangup
>> > >
>> > > ;
>> > > ;  implicit trunked call - here we could/should do an ENUM look
>> > > ;  up to see if we can place the call via IP and fall back to BT
>> > > ;  if not... just for now this isn't implemented and we always
>> > > ;  call
>> > > ;  out via BT!!
>> > > ;
>> > > exten => _0.,1,Dial(CAPI/g1/${EXTEN}/b)                    ; early B3
>> > > connect
>> > > always
>> > > ; exten => _0.,1,Dial(CAPI/g1/${EXTEN}/B)                   ; early
>> > > ; B3
>> > > connect
>> > > on success
>> > > ; exten => _0.,1,Dial(CAPI/g1/${EXTEN})                       ; no
>> > > ; special
>> > > options
>> > > exten => _0.,2,Hangup
>> > >
>> > > _______________________________________________
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>> > >
>> >
>>
>>
>

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