Calls being dropped to Local Landlines

[stsvoip318]

Hello,

Recently, within the past week or so, 3CX started issuing a BYE to our SIP provider (TelNyx) when calling local numbers. We have had over 10+ dropped calls. Here is the scenario...

1. It is only when we call out to the local numbers
2. If they call us, we do not drop a call
3. It is sporadic. Meaning, sometimes, when we call them, the call could last 10 seconds, 30 seconds, or a minute. There is no set time as to when the call drops.
4. If we call out to a cell phone, there is never a dropped call

Again, this started within the past week or so and our client is getting aggravated. Any ideas?

 

[leejor]

You have conformed that 3CX is dropping the call? Have you compared (perhaps Verbose setting ) a dropped local call, and one to a mobile that stays up, in the 3CX Activity Log?

I can't understand 3CX dropping calls selectively unless there is a "condition" coming from your provider.

 

[stsvoip318]

TelNyx, our SIP provider, did a deep dive with 6 different calls. They sent me PCAP and confirmed that the PBX (3CX) was sending them the BYE.

 

[rgruber]

You should be able to get a free test trunk from another provider to verify that its really 3CX. A lot of VOIP companies will allow you to test. If not, I may be able to get you one to test. Also, what version, edition and platform are you running 3CX? Just to double-check does your firewall check come back clean? Any updates on your gateway firewall? Do you have A/V running on the 3CX server? How old is your nic driver on the 3CX server? Make sure to update BIOS, Chip, and Nic drivers in that order. Take a phone and plug it into a core switch with the least amount of hops to the 3CX server, is it still dropping? A lot of questions, but it will help to determine what the problem is. Your title says "Local Landlines", just want to verify you are running direct SIP to 3CX, no voice gateway? Calling a cell phone doesn't drop? Thanks.

 

[stsvoip318]

Version 16.0.6.641
Amazon Lightsail Linux Debian 9
Firewall check is clean
No updates to firewall
no AV

Direct SIP to 3CX, then an SBC connection in the office. Only two phones and both are doing it. Calling a cell phone does NOT drop a call.

 

[leejor]

As I said, compare two calls, in the Activity Log, to different numbers, one that drops, and one that does not. What is different, other than the number?

 

[rgruber]

I would try another trunk or have your current provider set up a proxy on their end for your calls. What is your firewall brand on the user/phone side? Does your SBC ever drop? Also, like leejor said, what do the activity logs say?

 

[JohnS_3CX]

Hi,

It would be worth running a capture also on your PBX and catching one of these cases, this might give some hints as to why your PBX is sending a BYE message, and there could be a number of reasons behind it.

 

[stsvoip318]

I upgraded to the latest firmware last night. So far, they haven't dropped any calls. I will keep you posted

 

[stsvoip318]

Still no dropped calls since the updated firmware