Strange problem with PAP2T

[Bob Denny]

I have a couple of extensions on a PAP2T ATA (2 x FXS). Most of the time they work fine. Once in a while, when you pick up the phone, no dial tone. Looking at the PAP2T status page, it shows off-hook (correct). In the 3CX it shows Registered.

So one time I caught it not giving dialtone and decided to leave it off hook till something happened. After about 10 minutes, I got dial tone!! And 10 sec later I got the "you didn't do anything" re-order tone (correct). Looking at the 3CX logs, the ATA had just registered that extension.

I have the PAP2T set for registered timeout of 600 sec. I'm no SIP expert. I don't even know what "registered" actually means (beyond "the PABX knows this device is alive). I tried searching for "registered" "timeout" "extension" and combinations of these words but this forum says those words are too common and won't do the search.

There doesn't seem to be a setting in the 3CX for registration timeout (at least that I can find). And the PAP2T admin guide says 3600 is the default but it will be shorter if the proxy sends Min-Expires. Does the 3CX send that? Where is it configurable?

I apologize for this rambling message...

 

[leejor]

I haven't use the PAP2T but have used a number of other Linksys devices. Is there a Status page, like some of the others that actually says whether the device is registered and how many more seconds before it re-registers? I usually set devices on the same network to 3600 seconds. The system log leads me to believe that 3CX want devices to register more often, It hasn't been an issue with me so i haven't paid too much attention. Does the PAP2T have a setting to turn on syslogs? If so you may want to have a look at those. You may want to try "playing with the "registration required for dialtone" option, I'm sure it's called something else. See, if, when you place a call it just won't go through (even though you should get dialtone every time).

 

[Cjay]

the PAP2T admin guide says 3600 is the default but it will be shorter if the proxy sends Min-Expires. Does the 3CX send that? Where is it configurable?

Veering slightly off topic, that reminds me of an ongoing and perplexing problem: Why when all my phones are set to register ever 60 minutes do they appear to register every 30 instead?

Doing a Wireshark capture of the registration request shows:
sip.Contact == "\"Extn 100\" <sip:[email protected]:5060>;expires=3600"

However 3cx responds:
sip.contact.binding == "<sip:[email protected]:5060>;expires=1800"

Why would 3cx force an 1800 second registration interval despite the request being for 3600?

 

[Bob Denny]

Is there a Status page, like some of the others that actually says whether the device is registered and how many more seconds before it re-registers?

Yes... too bad I didn't notice whether it said it was registered. I suspect not because I don't have the equivalent of "dialtone if not registered" turned on, purposely.

The weird thing is that the 3CX said the extension was registered, yet the PAP2T thought it was not. This would mean the PAP2T dropped its registration before the 3CX checked again. This is a bit confusing as I indicated previously.

The good news is that it hasn't happened since I changed the PAP2T's registration timeout from 600 to 300 sec.

 

[leejor]

Normally you would only want dialtone if the ATA or phone was registered. then if you picked up the phone, as you found, and there was no dialtone, you'd know there was a problem. Just thought for testing you might be able to make calls but not receive them. There could be a problem with another timer, make sure that all others are at the default values. Some sites on the web have set up values that others have found to work well.

Try increasing the registration time a bit at a time until you have a problem again. I think that i also found that the devices register every 30 minutes. Haven't found any place to change that. A shorter registration time should not be an issue, I actually had a couple of ATA's that were registering every 60 seconds until i figured out how to upload a config file to them. Even then i couldn't get registration to go beyond 30 minutes.

 

[Bob Denny]

I'm still confused... can someone tell me who is in charge of registration? I think that the ATA (or any extension) registers with 3CX. I can find no timer on the 3CX setup that it uses to decide an extension is not registered after ___ time of not hearing from it. Right now my ATAs are registering every 5 minutes and the problem has not returned yet.

 

[leejor]

My understanding (and someone please correct me if I'm wrong) is that the the provider, in this case , 3CX, can set the registration time. If there is no time set (sent) by the provider or it is more than the ATA settings, then the setting in the ATA will be used. In other words, you can set it for less, but if 3CX says 30 minutes, you can't set it higher.

Anyone else?