Ringing an extension rings multiple extensions at the same time

fapb48

SMB User
Joined
Feb 24, 2025
Messages
6
Reaction score
1
Hi,

We seem to be having an issue that happens quite often, and I can't figure out why it's happening.

If someone rings EXT 3215, for example, it rings that EXT but also rings EXT 3218, even though they are 2 completely different physical phones.

What am I missing here?

Thanks for your help
 
Are these phones connecting via the 3CX SBC? They shoudl be configured to connect through a 3CX SBC, or a router phone.

I'm suspecting you have them configured directly onto the PBX without an SBC, and without these being router phones.
 
  • Like
Reactions: Evolute IT
Are these phones connecting via the 3CX SBC? They shoudl be configured to connect through a 3CX SBC, or a router phone.

I'm suspecting you have them configured directly onto the PBX without an SBC, and without these being router phones.
I'm sorry if I sound a bit dumb, but how would I go about finding out if that's the case?

We have around 100 phones, and only a couple are having this issue. But I'm not quite sure how I would check if the phone is properly configured to use 3CX SBC instead of PBX.

Thanks
 
100 phones? I am going to assume that you dont have an SMB installation then (This was opened under the SMB)

First of all, are the phones in the same network as the PBX? In that case you wouldn't need an SBC. The same would apply if you have any remote sites VPNed between them.

If the phones are in a separate network to the PBX, you can check the phones page, and see the IP Address they are connecting from.

If you see the devices connecting via SBC, then they are conencted via the SBC. The 3CX SBC is a software package that is installed on a machine in the remote network, to establish a secure connection between that site and the PBX. This can also be done on some phones that can be configured as router phones. Not all phones have this capability however as it is hardware and firmware dependent.

In the phones page, if you see a public IP address (the public IP Address of the network the phones are connecting from) then this would explain the issue you are facing.

This is what we call a STUN configuration, and this is a very insecure and problematic way of configuring the phones, if not done properly.
 
100 phones? I am going to assume that you dont have an SMB installation then (This was opened under the SMB)

First of all, are the phones in the same network as the PBX? In that case you wouldn't need an SBC. The same would apply if you have any remote sites VPNed between them.

If the phones are in a separate network to the PBX, you can check the phones page, and see the IP Address they are connecting from.

If you see the devices connecting via SBC, then they are conencted via the SBC. The 3CX SBC is a software package that is installed on a machine in the remote network, to establish a secure connection between that site and the PBX. This can also be done on some phones that can be configured as router phones. Not all phones have this capability however as it is hardware and firmware dependent.

In the phones page, if you see a public IP address (the public IP Address of the network the phones are connecting from) then this would explain the issue you are facing.

This is what we call a STUN configuration, and this is a very insecure and problematic way of configuring the phones, if not done properly.
Thank you for the great explanation, and I apologise for opening the thread in the wrong category.

All our phones are configured with SIP Direct (STUN Remote), and we get a provisioning link which is provisioned against all devices.
 
That would be the issue right there.

I would suggest getting an SBC at the remote site, and the phones provisioned through that.

Otherwise the proper configuration entails unique ports on each of the extensions configuration, both at the PBX provisioning page, as well as unique port forwarding of these ports at the remote side. This would also require the phones to have a static IP Address on their remote network.

The issue your facing is due to a port mismatch which the remnote firewall is chucking its dollies out of the pram and forwarding the traffic willy nily without any rhyme or reason.

Just out of curiosity, are all 100 phones on 1 network? Or dispersed?
 
That would be the issue right there.

I would suggest getting an SBC at the remote site, and the phones provisioned through that.

Otherwise the proper configuration entails unique ports on each of the extensions configuration, both at the PBX provisioning page, as well as unique port forwarding of these ports at the remote side. This would also require the phones to have a static IP Address on their remote network.

The issue your facing is due to a port mismatch which the remnote firewall is chucking its dollies out of the pram and forwarding the traffic willy nily without any rhyme or reason.

Just out of curiosity, are all 100 phones on 1 network? Or dispersed?
We have phones distributed across four physical locations.
I am just perplexed as to why this has started happening lately, which has never been an issue before.
 
Thats due to the nature of the firewalls. An IP Address may have changed on the phones, the firewall may have reset a connection and messed up with the mapping.

Thats we recommend against configuring STUN devices, and goign through the SBC.
 
That would be the issue right there.

I would suggest getting an SBC at the remote site, and the phones provisioned through that.

Otherwise the proper configuration entails unique ports on each of the extensions configuration, both at the PBX provisioning page, as well as unique port forwarding of these ports at the remote side. This would also require the phones to have a static IP Address on their remote network.

The issue your facing is due to a port mismatch which the remnote firewall is chucking its dollies out of the pram and forwarding the traffic willy nily without any rhyme or reason.

Just out of curiosity, are all 100 phones on 1 network? Or dispersed?
I see what you mean.. The 2 EXT are using the same Local SIP Port.
Is there a way to export these from all the phones? To make it easier to investigate, which phones are configuring under the same port?
 
You would have to go and see each individual extensions settings.

Also, in Version 20 we removed the configuration of STUN altogether, and this would require a custom template to be made in order to keep working.

Your best bet would be to bite the bullet and deploy an SBC at your sites. That way you will never have issues like this, nor would you need any firewall configuration at the remote sites.

The SBC works in the same way the 3CX Mobile apps, by using the tunnel, just without the fancy interface and presence.
 
You would have to go and see each individual extensions settings.

Also, in Version 20 we removed the configuration of STUN altogether, and this would require a custom template to be made in order to keep working.

Your best bet would be to bite the bullet and deploy an SBC at your sites. That way you will never have issues like this, nor would you need any firewall configuration at the remote sites.

The SBC works in the same way the 3CX Mobile apps, by using the tunnel, just without the fancy interface and presence.
Thank you very much.
We have contracted a third party to set up and maintain the service for us. I will raise this with them and ask why we are still using an unsecured provisioning method.
Thanks again for all your help
 
  • Like
Reactions: NicholasP_3CX

Members Online Now

Forum statistics

Threads
111,832
Messages
589,283
Members
164,662
Latest member
DejanMDS