IAX trunk suddenly behaving oddly

After months of working super reliably, an IAX trunk is now behaving most oddly. It’s a trunk between two FreePBX servers that uses ZeroTier.

Now when I call home from work from one of the Digium D50s there, the phone at home (which is a POTs telephone connected via an ATA) rings but if you answer it it keeps on ringing. Occasionally if you answer it, I can hear my wife, but she can’t hear me. Mostly, though, it just rings and doesn’t stop ringing when you lift the handset.

HOWEVER, internal calls within the home to that POTS connected to that ATA behave perfectly normally.

STRANGER STILL, calls I make from my mobile using a DISA to that POTS phone connected to the ATA work normally.

Even WEIRDER, calls I make from a softphone on my laptop when I’m connected to the WORK FreePBX instance using ZeroTier which then do a 180 and call HOME (so essentially I’m calling home from home but via work) ALSO work totally normally.

Totally stumped.

Wanna seem my logs?! I don’t know what I’m looking for.

Many thanks if anyone can be bothered…just really strange why this would start happening out of the blue. It sucks! I’m in trouble with SWMBO

I’d contact Digium/Sangoma as a warranty hardware problem. While there’s no guarantee that this is the issue, you’re correct in that the one-way audio is a problem and may well be a new one. That fact that the phone continues to ring after you pick it up seems like an important clue.

Probably going to require looking at debug/signalling traces between the two systems. Are you experiencing higher than normal packet loss across the connection between them?

Matthew Fredrickson

hmmm - so it’s not JUST IAX, it seems.

It worked well for a week or so and I thought I’d cracked the problem by resetting all the ATAs.

Anyway out of the blue, problems again. I rang home from work over the IAX trunk and the POTs phone connected to the ATA (and then FreePBX) wouldn’t answer the call. At my end I just heard constant ringing tone.

Next I tried calling in from my mobile phone DISA inbound route. This time the call could be answered and I could hear my wife but she couldn’t hear me.

Is this more likely to be the ATA’s fault than FreePBX?

I have the two traces here:

Call wouldn’t answer at all
I couldn’t be heard but I could hear my wife

Suffice to say it seems to be JUST this one phone in the house that gives problems. But it’s the second line on an ATA that works fine for the other line. Is there any chance a dodgy wiring connection could give these symptoms? It seems unlikely to me.

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