SBC Issue

[BCS Tech]

For the past 3 weeks, I have been having an issue with as SBC at one of our customers being connected to the wrong PBX public address. Has happened about 5 times.

The customers PBX name is XXX.al.3cx.us hosted at Digital Oceans
Correct public IP address for the PBX is XXX.241.133.76.

Several times over the last couple of weeks. the SBC has disconnected from the PBX and reconnected (online) using a different IP address. This morning, it was connected using 47.36.245.174. The internal proxy address on the physical phones changed from the internal 192.168.10.6 ip address to 192.168.18.164. Phones were offline, but the SBC is online in the 3CX SIP trunk section, but shows the 47.36.245.174 address which is wrong for the public ip of the customer.

Here is a copy of the event log when the SBC changed the connection. Never says Sip trunk down, between the 2 events.

Trunk SBC 'Wade SBC' (47.36.245.174/192.168.18.164) has changed status to Up
SBC / Tunnel ID: 4102 10/01/2022 12:29:52 PM

Trunk SBC 'Wade SBC' (XXX.209.61.105/192.168.10.6) has changed status to Up
SBC / Tunnel ID: 4102 10/01/2022 10:38:37 AM

I stopped and restarted the SBC and then the phone came back online with the correct internal SBC address.

I thought maybe there was an issue with the Server 2019 the SBC was running on, so I moved it to another server on Saturday morning. The same issue again. The event shown above happened after I moved the SBC.

How can this information change and how do I stop it?

I am at a loss. Any help would be appreciated.

Thanks

 

[Evolute IT]

Do they have a multi-WAN setup by any chance? Or VLANs?

Internal IPs don't tend to change this way. External ones can tho, but it's usually not a big deal.

 

[BCS Tech]

We installed the internal networking in May when we took over the account. Nothing internal but a Cisco firewall and some dumb switches. Only 6 computers and 6 phones.

 

[SyncWave]

Are you on update 5? They don't allow you to assign it static as you wish anymore. It has to be exactly as the SBC shows up as in the trunk section.

 

[BCS Tech]

What do you mean "They don't allow you to assign it static as you wish anymore"?

Yes, 18.0 update 5

 

[SyncWave]

What do you mean "They don't allow you to assign it static as you wish anymore"?

Yes, 18.0 update 5

You used to be able to type in whatever you want based on your design for the SBC configuration of an extension. Now that is no longer a text box, its a drop down based on 3CX connected SBC's and the FQDN or IP they show up as in the trunk section. I haven't played with it that much yet since the final to test its behavior when one goes offline, it updates, or whatever.

 

[BCS Tech]

Ok, I understand what you are referring to. And that is the problem. The internal proxy ip address on the phone changed when the public ip address of the connected SBC changed in the 3CX console.

The correct SBC info is
XXX.209.61.105/192.168.10.6

the wrong address was
47.36.245.174/192.168.18.164

I want to know how the public ip address of the SBC changed in 3CX.

 

[SyncWave]

I'd have to know a lot more details to help with sorting that out, I'd contact your 3CX partner.

 

[BCS Tech]

Anyone else have any suggestions. I checked the log files and the first time the issue happened was on 9/16. Since then, it has has switched to the wrong ip address, (not always the same wrong ip address) 14 times. The system ran without any problems for several months prior to this.

How does and SBC register with 3CX. Seems like the SBC would need the http address of the PBX and the secret key in order to register as online on the PBX.

Any help from a 3CX person on this?

 

[ivank]

Hi [email protected]!
It seems your SBC credentials leaked out and someone else is trying to connect on behalf of your SBC (provided that you have no idea where the wrong IPs are coming from). I'd suggest to create a new SBC Trunk on PBX, and reinstall the SBC using new link. Then reprovision the phones using the new SBC connection.

 

[ivank]

Also make sure that the machine hosting the SBC has only one network interface left, i.e. disable any Wi-Fi, 3G modems etc. to make sure that SBC always uses the same physical connection.

 

[BCS Tech]

Thanks. I will do this.