[asterisk-users] Second invite after 100ms (with default t1min=100) --> canceled call problem!

[Michael Maier]

Hello!

I encounter the following problem (asterisk 11 and 13) with Teconisy as
trunk provider with enabled qualify and default t1min (100ms):

Teconisy most often doesn't answer the first invite before asterisk
default t1min ended. Therefore asterisk sends one more invite. This
second invite is answered by Teconisy with

status 486 - Request terminated - Channel limit exceeded.

(The second invite obviously is interpreted as second, new call).

Asterisk therefore cancels the first(!!) call - but Teconisy proceeds
with exactly this first call (which now can't be handled by asterisk any
more).

For me, there are two problems in asterisk at this point:

1. The VoIP standard defines 500ms for t1 - using this standard value
   for t1min works fine with Teconisy, too. t1min should be always
   500ms - it prevents a completely blocked line!

2. Why does asterisk stop the call completely after the second invite,
   which is canceled by Teconisy? It should be ignored because it
   means, that the first invite is already processed by Teconisy.


Btw: I can see the same behavior with German Telekom. Asterisk most of
the time sends two invites, too, but here I don't get an error back from
Telekom, because I have two channels and therefore the channel limit
isn't exceeded most of the time. Setting t1min to the VoIP standard of
500ms prevents these unnecessary double invites with German Telekom, too.


Therefore: Please use the standards compliant t1min=500 instead of the
not compliant value of 100, which can cause much trouble and which
creates totally unnecessary network overhead.

Or is there another solution I overlooked?


Thanks,
Michael Maier