SIP Trunk: Where/how do you set the re-registration time interval?

FreePBX Providers
1

I have a SIP Trunk that is registering to a provider and it re-fires about every 600 seconds.
I am looking to adjust this (typically lower) to keep a NAT connection alive.
Under settings for the SIP Trunk itself we have PJSip settings then advanced.
Available related settings appear to be “Expire” and possibly “Qualify Frequency”
If I set either (or BOTH) of these to a lower number (45 and 55 for example),
Save/Commit/reboot etc.
I am still seeing the re-registration only happening every 600 seconds.
What am I missing?

Test-Trunk/sip:test-sipprovider.com Test-Trunk Registered (exp. 599s)

Thanks!

2

The registrar can override the suggested registration interval. The provider may do so to limit the load on their servers.

You should check the detailed logs to see if this is what is happening.

3

Setting qualify frequency to n seconds results in a a SIP OPTIONS message being sent to the remote every n seconds. AIUI this, if sufficiently frequent, is enough to keep the NAT session alive too.

4

There’s also a global pjsip advanced setting for keep-alive.
I’m guessing this would also be applied to any/all registering SIP trunks?
Setting the SIP -re-registration interval was the really old-school way of doing this.
And I don’t ever remember the far end/remote provider somehow overriding this or keeping it from happening.
First time I have ran into or noticed this.
Used to always work a long time ago.
If I set re-register every 50 seconds it used to just do it.

5

For outbound providers some certainly did, in many cases forced it low to get around NAT. As David said, an actual trace would show what is actually happening - what Asterisk has requested.

6

I’ll end up doing a trace and packet capture at some point soon.
The provider is indeed kicking it back at me saying that I can register as frequently as I want and that they are not “doing anything” in this regard.
It’s not causing me any problems at this point but I’m trying to learn what’s going on and why it only registers every 600 seconds on the dot.

7

From an Asterisk perspective, our default is actually 3600 seconds[1], but of course FreePBX could override that too.

[1] res_pjsip_outbound_registration - Asterisk Documentation

8

There’s not any hard-coded minimum in FreePBX is there?
I’m set to re-reg every 40 seconds at the moment.
I could see that possibly reverting to 600 seconds or some default if my setting is out of range.
But this is the first time I have run into this issue.
I’m also new to FreePBX itself so this is the first time I have noticed any such thing in FreePBX.