How Setup Phones to go to an offsite PBX

[bluepoet]

I have our PBX up and going for the most part. Just trying to now resolve the issue on how to get a phone to connect and communicate correctly to an offsite PBX. Is that an option and if so what is the best way to accomplish this?

Would I install a office sip at the locations we wanted the phones and then create a gateway to that?

 

[hfoster]

I'm not entirely sure what you are asking here, I think you are trying to connect FusionPBX to another PBX? If you want to send traffic to another PBX you can create bridges to the other PBX.

Bridges - FusionPBX Docs

They will need to be able to talk to each other, so you will need to consider secure ways of doing that (firewall rules, portforwards or VPNs).

 

[bluepoet]

I'm not entirely sure what you are asking here, I think you are trying to connect FusionPBX to another PBX? If you want to send traffic to another PBX you can create bridges to the other PBX.

Bridges - FusionPBX Docs

They will need to be able to talk to each other, so you will need to consider secure ways of doing that (firewall rules, portforwards or VPNs).

Thats what I was thinking. Basically the PBX is at a remote site and we want the phones from our other locations to be able to go to it and function. So 1 PBX but the phones are coming from remote locations behind a firewall /nat network. I found something called officesip that may be a way to bridge the gap. I think my supervisor was hopeful that the phones would just magically work behind a NAT Firewall as long as they can initially connect to the PBX system.

 

[hfoster]

Ah, right. What you're thinking of is similar to how 3CX does things. They have an 'SBC' which creates a tunnel back to a 3CX. Now you *can* do something like that where you proxy requests through a device, however you don't need to do this for FusionPBX. Other PBXs need it because they can't do NAT traversal as well.

You'll need to forward port 5060 to the FusionPBX server (your choice to lock it down to an IP address), and ensure RPORT is enabled on the handsets (should be if provisioned from FusionPBX) and it should be fine. FreeSwitch has a ton of fixes for NAT traversal which makes the generic advice for telephony a bit moot.

You may need to play with some settings on some janky routers that have SIP ALGs and stuff, but for the most part it's very smooth.

 

[bluepoet]

Gotcha - so it is possible to do - just need to make some adjustments to forward 5060 to the remote server. Thanks - ill give that a try and see what happens.

 

[bluepoet]

I tried port forwarding rules to the PBX but still no luck - I didn't see a RPORT option on the grandstream phones we have. Its just weird that they connect to the PBX just the PBX cannot send packets back to them. Wonder if there is something in the tables for the fail2ban that I need to scope out.

 

[hfoster]

It's more likely the firewall the phones are behind. Firewalls despise UDP packets on random ports, like RTP. Very few of them are tracking the SIP SDP messages to open sockets. I would recommend creating a rule on any pertinent firewall to permit traffic from the source IP of the PBX and vice versa if necessary.

Here's the specific ports if you want to restrict it to ports: https://docs.fusionpbx.com/en/latest/firewall.html

 

[bluepoet]

Okay - ill go back to the firewall and see if I can see anything. Its a PFSense firewall. I think have the ports all opened but it doesnt hurt to make sure. Thank You.

 

[hfoster]

You've also got the option of a VPN into the network where the FusionPBX server is. Not always feasible, but incredibly helpful if you do. Encryption and bypasses NAT issues.

 

[bluepoet]

I thought about that as well - seeing that the phones have the option for OpenVPN. Just trying to find the most simple approach. But as always, simple doesn't always equate when your doing projects like this.

 

[bluepoet]

Hfoster - I found the issue - there is a package that I needed to install on the PFSense firewall and once that package is installed - everything is working as it should.. thank you for all of your help. Now I just have one more question to find out about and then i'll be set.