[Asterisk-Dev] r option issue in app_dial

[Armin Schindler]

On Tue, 13 Dec 2005, Gil Kloepfer wrote:
> I normally don't send along info to the list when I find a new bug (I
> suppose I should), but this one may catch some of you off-guard:
> 
> I discovered the other day that if Dial is used WITHOUT option 'r'
> Asterisk still provides ring progress tones to the caller.  Additionally,
> it does so without muting the channel audio (what happens when 'r' is used).
> 
> By itself, this is a bug, but unfortunately I suspect many people have:
> 
>       exten => 1234,1,Dial(SIP/1234)
> 
>   instead of
> 
>       exten => 1234,1,Dial(SIP/1234||r)   -or-  Dial(SIP/1234,,r)
> 
> 
> inside their extensions.conf file and have depended on the fact that
> the ring progress happened to be provided even though they didn't
> specify 'r'.
> 
> I have provided a patch to fix app_dial (see bug ID #0005979) so that
> ring progress is handled as documented.  When this is committed (I hope
> it is) many people will likely report that callers aren't hearing ringing
> which will be due to ommissions in the dial plan (like demonstrated above).
> 
> I discovered the bug since I have two Asterisk boxes between our SIP
> phones and the telco.  If I specify 'r' the line has the ringing feedback,
> but users never hear the telco informational progress messages (like 'the
> number you have reached has been disconnected').  All they hear is
> endless ringing.
> 
> If I properly remove 'r', then Asterisk still was generating the ringing
> sound (bug), but the channel was unmuted (as it should be) and the telco
> ringing and Asterisk ringing were mixing together to form a very odd
> ring sound which was confusing our users.
> 
> The "r" option for Dial() should only be specified on the terminal
> Dial application -- that is, the Dial that actually addresses a physical
> phone.  All other Dial() in between should not have "r" so the caller
> can hear the actual progress tones generated by the last PBX or switch
> in the chain that drives the physical device.  This is a very subtle
> point that I don't think many people understand.
> 
> Anyhow, I hope this isn't too much for the -dev list, and that it
> helps give the developers a heads-up on this.  The proper use of
> Dial(tech||r) should probably be in the docs or in the sample
> extensions.conf somewhere.

I don't think your patch is correct. With your patch applied, the 
caller-channel does not get the information about the called party is
ringing, which is sometimes needed.
Producing ringing sound and signaling the ringing event are two different
things.

Armin