[asterisk-dev] ISDN Overlap dial mechanism

[Kevin P. Fleming]

Moises Silva wrote:
> I am very interested in hearing comments about this too. It's been a
> couple of months now since I have been thinking in an early bridge
> functionality, particularly for R2 signaling sometimes the call setup
> times can be long and there are situations where users just need to
> pass-through the call to the telco from a PBX for certain dial
> patterns. (PBX -> R2 -> Asterisk -> R2 -> Telco)
> 
> So, for example, pattern _1XXXX should be handled by Asterisk to
> Playback() or Dial() to a SIP extension, but, for pattern _9. the call
> should go straight to another Zap device connected to the telco. The
> situation can get pretty slow in R2 variants where there is no way for
> the calling end to say "I have no more digits to send" and the variant
> relies in time out.
> 
> When the incoming leg sees it has received a 9 as first digit should
> be able to spawn the PBX thread and do an early bridge to some other
> DAHDI chanel to speed up the call setup process. Probably a
> DAHDIBridge() application where the particular DAHDI signaling
> implementation would handle such request.
> 
> I'm sure there are details I have not considered, but I think it's doable.

chan_dahdi already supports overlap dialing on ISDN, and this is used
heavily in Europe due to the need to support variable length numbers
being dialed. Following the same logic for MFC/R2 in chan_dahdi
shouldn't be that difficult. It does not require any special dialplan
applications at all.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
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