[asterisk-dev] Overlapped dialling on SIP trunks for outgoing calls

[Andreas Brodmann]

2008/4/25, Kevin P. Fleming <kpfleming at digium.com>:
>
> Andreas Brodmann wrote:
> > After chasing a problem I looked at the SIP code (1.4.19)
> > with a colleague and as far as we understood it, overlapped
> > dialing on sip trunks for outgoing calls is not supported (yet?).
>
>
> I have never heard of 'overlapped dialing' on SIP. SIP is always
> en-block dialing.
>
> Can you provide any references for what you are talking about?
>
> --
> Kevin P. Fleming
> Director of Software Technologies
> Digium, Inc. - "The Genuine Asterisk Experience" (TM)


Kevin,

in sip.conf you can set 'allowoverlap=yes'

If a phone is configured accordingly (early dial) it will send an INVITE
request
for each key a user presses. e.g. 1 at asterisk, 11 at asterisk and then
111 at asterisk.
For each incomplete INVITE asterisk will return 484 "Number incomplete"
until the
client sends a number which is complete (e.g. matches a pattern).

This works fine until a client tries to call a number that asterisk reaches
via a sip trunk to
another pbx (or carrier), whereas the length of the number is unknown:
// e.g. International Calls
e.g. exten => 000!,1,Dial(SIP/${EXTEN:1}@carrier,120)

in this case, asterisk will send an INVITE to the carrier after the first 3
zeros. The answer
from the carrier will be 484 (number incomplete). Instead of forwarding this
response to the
phone asterisk will end the call -> congestion.

---
Andreas Brodmann
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.digium.com/pipermail/asterisk-dev/attachments/20080425/c035a48d/attachment.htm