asterisk users - Nov 2019 - PJSIP device_state_busy_at, how does this work?

Hi Gang

According to:
https://wiki.asterisk.org/wiki/display/AST/Asterisk+13+Configuration_res_pjsip#Asterisk12Configuration_res_pjsip-endpoint_device_state_busy_at

And endpoint should return busy if this number is reached.

We have PBX Trunks registering to the Asterisk.

So we want to limit the number of concurrent calls to a PBX and return
busy, if more than the configured number of channels are in use.

I set for example:

device_state_busy_at=4 to limit the trunk to 4 channels so 400kbit/s
can be assured by QOS measure.

But when testing, I noticed caller don't get busy.

pjsip show endpoints happily shows 5 of 4 channels in use.

Do I have to query the device state from the dialplan and manually
return busy?

Mit freundlichen Grüssen

-Benoît Panizzon-
-- 
I m p r o W a r e   A G    -    Leiter Commerce Kunden
______________________________________________________

Zurlindenstrasse 29             Tel  +41 61 826 93 00
CH-4133 Pratteln                Fax  +41 61 826 93 01
Schweiz                         Web  http://www.imp.ch
______________________________________________________

On Thu, Nov 28, 2019 at 10:32 AM Benoit Panizzon <benoit.panizzon at
imp.ch>
wrote:
> Hi Gang
>
> According to:
>
>
https://wiki.asterisk.org/wiki/display/AST/Asterisk+13+Configuration_res_pjsip#Asterisk12Configuration_res_pjsip-endpoint_device_state_busy_at
>
> And endpoint should return busy if this number is reached.
>
> We have PBX Trunks registering to the Asterisk.
>
> So we want to limit the number of concurrent calls to a PBX and return
> busy, if more than the configured number of channels are in use.
>
> I set for example:
>
> device_state_busy_at=4 to limit the trunk to 4 channels so 400kbit/s
> can be assured by QOS measure.
>
> But when testing, I noticed caller don't get busy.
>
> pjsip show endpoints happily shows 5 of 4 channels in use.
>
> Do I have to query the device state from the dialplan and manually
> return busy?
>
The option strictly controls device state. Any enforcement of a limit for
calling does not exist, and is up to you to do using various methods.
Device state could be queried and used, or GROUP[1] and GROUP_COUNT[2].

[1] https://wiki.asterisk.org/wiki/display/AST/Asterisk+17+Function_GROUP
[2]
https://wiki.asterisk.org/wiki/display/AST/Asterisk+17+Function_GROUP_COUNT

-- 
Joshua C. Colp
Senior Software Developer
Sangoma Technologies
Check us out at www.sangoma.com
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Hi Joshua
> The option strictly controls device state. Any enforcement of a limit for
> calling does not exist, and is up to you to do using various methods.
> Device state could be queried and used, or GROUP[1] and GROUP_COUNT[2].
> 
> [1] https://wiki.asterisk.org/wiki/display/AST/Asterisk+17+Function_GROUP
> [2]
> https://wiki.asterisk.org/wiki/display/AST/Asterisk+17+Function_GROUP_COUNT
Yes, I had a shot at GROUP and GROUP_COUNT but somehow did not manage
to achieve efficient control of the channels.

I have hacked together an ugly solution.

I use an agi script for routing decision.

If the call originates from a Customer Device:
($tech,$device,$callid) = $chan_vars{'channel'} =~
m/([A-Za-z]*)\/(.*)?-(.*)/;

So $device contains the part I need to use in:

$AGI->get_variable("DEVICE_STATE(PJSIP/$device)");

If this returns BUSY, I send the call to HangUp(17)

On calls TO a Customer Device, I use the same $device to build the
destination URI: Dial(PJSIP/$destination@$device) and therefore I can
also query the state and figure out if I need to send the call to
HangUp(17).

One interesting observation. If the count of channels is not at the
limit (eg 2 of 2 => busy), so for example 3 out of 2 channels, the
status does not stay ab BUSY but goes back to IN_USE. Shouldn't that
still be busy? :-)

Mit freundlichen Grüssen

-Benoît Panizzon-
-- 
I m p r o W a r e   A G    -    Leiter Commerce Kunden
______________________________________________________

Zurlindenstrasse 29             Tel  +41 61 826 93 00
CH-4133 Pratteln                Fax  +41 61 826 93 01
Schweiz                         Web  http://www.imp.ch
______________________________________________________