[asterisk-users] Overlap SIP dialing

[Kevin P. Fleming]

On 09/07/2011 11:06 AM, Daniel Tryba wrote:

> The aim of the quest for overlap dialing is to let the user enter a
> number at their own pace but immediatly dial when all digits are
> received (just like plain old ISDN does). My trunk is a bunch of E1 PRIs
> in overlap mode. The following just works for any SIP client (without
> overlap dialing):
> exten =>  _X.,1,Answer()
> exten =>  _X.,n,Dial(${TRUNK})

Unless I'm mis-remembering, this was the point of adding the '!' 
dialplan match character. If you use _X!, and you have your SIP 
endpoints configured to send an INVITE as soon as the user has entered 
two digits (and you have no other patterns in the context that could 
match), then the dialplan will match against that and initiate a Dial() 
on your ISDN PRI. Since the number is not yet complete, the SETUP 
message on the PRI won't result in the call proceeding, and as the user 
of the phone presses additional digits they'll be sent to Asterisk as 
DTMF, bridged over to chan_dahdi, and it will send them as INFORMATION 
messages rather than as DTMF digits, because it knows the outbound call 
is still in 'dialing' state.

However, this is still going to 'mess with CDRs' as you put it, because 
the only switch in the network that knows the complete number that was 
dialed is the PSTN switch that your PRI is connected to. It seems 
possible that chan_dahdi could 'update' the EXTEN on the current channel 
as the additional digits are dialed so that the CDR contains the 
complete number, but I have no idea whether it does or not.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
Jabber: kfleming at digium.com | SIP: kpfleming at digium.com | Skype: kpfleming
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at www.digium.com & www.asterisk.org