Inbound call problem


I have posted about this before but I have unfortunately not yet managed to identify the root cause of this problem. Sometimes, I’ll receive an incoming call and it will ring a Ring Group, but the call will get lost and there will be loads of “1 second calls” from “unknown”. If I pick up one of the phones, all I will hear is the dial tone, whilst the other phones in the group will still be ringing.

It’s such a strange problem and I am still quite new to FreePBX, so I am not totally familiar with troubleshooting the routing of calls. When I look at the CDR Report though, it shows 4 “1 second calls” with the callers CID and then the rest is 1 second calls, all with unknown CID? Even though this was a scam call, I’ve covered the number in the screenshot but where there is red, is where FreePBX had the callers CID and this shows on the phones on the first 4 rings, but then shows “unknown” for the remaining 1 second calls.

I would much appreciate any help that I could be given with this.


Just encase anybody else has the same / similar problem as I had here, I think I have managed to resolve it by following the steps provided by @Stewart1 on one of my previous threads - FreePBX and Grandstream HT813 - #9 by Stewart1. I have not experienced this strange problem since applying the configuration mentioned by Stewart. Thank you @Stewart1!


Just to add to this, the above unfortunately did not fully resolve the problem but changing this value on my Grandstream HT813 appears to have fully resolved it.


I had this set to “2”, which I have changed back to “6”. Since changing this, the weird call looping has stopped. I noticed this timeout showing in the syslog output of the HT813 and it was after two seconds, the call would go crazy.

Why do you mess around with these adapters and don’t simply get you a sip-trunk?

I am an IT Analyst, so this isn’t my area of expertise. I am relatively new to this area and started it purely through interest of wanting to learn more about digital phone systems. I only use my set up at home and one of the main reasons I went down this path was to properly combat scam/nuisance calls, along with having the added benefit of having phone hardware anywhere that has power/power over Ethernet/Wi-Fi.

I am a medical doctor by training :wink:
Have been using freePBX at several locations for many years, but I am no pro.
I usually install it on Intel-NUCs (Linux Mint) as a Virtualbox machine.
At home I ported the phone number to a SIP-trunk provider too.
It is amazing how reliable and stable this free software is…

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