[asterisk-dev] Dialstate without Ringing

[Paul Cadach]

Hello,

Edwin Groothuis wrote:
[skipped]
> According to him, the "Progress Description: Inband information or
> appropriate pattern now available." means that there is a B channel
> available now and you should start ringing instead of waiting for
> an ALERT. He also says that this behaviour only shows with analogue
> end-points.

NO!!! "B channel available" means switches/PBXes established backward voice path from terminating switch.

[skipped]
> The Q.931 specification says:
>
>     The user need not attach until receiving a CALL PROCEEDING/SETUP
>     ACKNOWLEDGE/PROGRESS/ALERTING message with the progress indicator
>     No. 8, in-band information or appropriate pattern is now
>     available, or progress indicator No. 1, call is not end-toend
>     ISDN; further call progress information may be available in-band.
>     Prior to this time, the network cannot assume that the user has
>     attached to the B-channel. After this time, the user shall be
>     connected to the B-channel, *provided the equipment does not
>     generate local tone*.  Upon receipt of the CONNECT message, the
>     user shall attach to the B-channel (if it has not already done
>     so).
>
> *'s are mine. What do they mean with "does not generate local tone"?
> Anyway...

"Do not generate local tone" means calling switch just bypasses voice from called switch and DOES NOT PROVIDE any
locally-generated tones (because voice path has established).

> When a CALL PROCEEDING comes in, with a 'progress indicator No 8',
> I think it's time to start ringing. Now of course people start
> saying "but there is so much you can do on the channel besides
> ringing", yes this is true. But we're talking about a non-ISDN
> remote here. Maybe only running when 'progress indicator No 8' and
> 'progress indicator No 2' are there?

For non-ISDN remote calling tones should be provided inband by called (remote) switch.


WBR,
Paul.