Port Forward needed on remote router from remote phone use

[Anthony - Sedcom]

A couple of weeks ago my manager did a port change on the office router coursing a remote phone (Yealink T48U) to stop working

I reverted the settings on the router and factory restarted the phone and unable to get it back on line

I was seeing RPS requests hitting 3CX no issue but the phone did not ask for user and password and connect

So now to last night and today

I was working on the phone at the office on a second internet connection and was not able to get it up and running

So watched though the V18 Stun Server / Remote phone setup video and i had everything all good

Then I watched the video a second time then cached it

They said I need to also have port forwards on the remote phones router?????

WHY?????

So Setup port forwards on my test internet and BOOM it started working and registering back to my office 3CX system

Now this will course all types of issues for remote workers that would like to use an office phone at home. You will have to place a port forward on every users home router for this to work.

So to my question has anyone else ran into the issue of needing a port forward on the remote phones router????

 

[ChrisC_3CX]

They said I need to also have port forwards on the remote phones router

When using the STUN provisioning method we do indeed require port forwarding on the remote site in order to ensure reliable communication between the IP Phones and the 3CX PBX. That is not to say that there aren't situations where everything will just work regardless of whether the remote firewall configuration was implemented or not, however, we do not recommend doing so nor do we support it as you will be relying entirely on your firewall to dynamically take care of the communication. That said, due to the variety of available firewalls out there, we cannot guarantee that this will be the case every time and that is why the remote firewall configuration is a requirement as it gets rid of any ambiguity and firewall behavior dependency.

 

[Alphabetic]

Because some firewalls support uPnP and some are stricter.

Some firewalls have SIP ALG which also cause problems.

https://www.3cx.com/community/threads/3cx-remote-stun-ip-phone-all-config.65632/

 

[leejor]

In most cases, using a single SIP device (STUN), behind a remote router, will not require any port forwarding at that site. However, with the myriad of possible home installations, that can always change. In some cases, home uses get their phone service though a router/ATA device, which can affect an additional SIP device.

In some cases, home uses (or unbeknownst to them, their offspring), have made changes to the router, that can have a detrimental affect on added SIP devices.

Lots of variables involved, so, unfortunately, there is no one-size-fits-all, especially when you have no (or limited) control, over the remote end.

 

[Clément Rousseau]

You all describe well why its recommanded but sometimes not mandatory. But what I don't understand is how others operators do without theses remote/local forwarding ? Lot of telecom operators do that without forwarding on remotes sites and its works great for them. Its a big drawback for 3cx!

 

[SweetAction]

For more information on stun and why/when it doesn't work as "plug and play" I would read this thread: https://www.3cx.com/community/threads/sbc-x-stun-which-and-when-to-use.77933/post-356680

As to how others handle, they do a SBC - but on server side (3CX does SBCs on client side if you want)

You could do a server side SBC with 3CX if you want - natpass is a popular option - but none are supported or bundled.

 

[Evolute IT]

You all describe well why its recommanded but sometimes not mandatory. But what I don't understand is how others operators do without theses remote/local forwarding ? Lot of telecom operators do that without forwarding on remotes sites and its works great for them. Its a big drawback for 3cx!

For more information on stun and why/when it doesn't work as "plug and play" I would read this thread: https://www.3cx.com/community/threads/sbc-x-stun-which-and-when-to-use.77933/post-356680

As to how others handle, they do a SBC - but on server side (3CX does SBCs on client side if you want)

You could do a server side SBC with 3CX if you want - natpass is a popular option - but none are supported or bundled.

Just to add to this: even the other providers, with cloud SBCs, have issues sometimes. Nothing is perfect and it all depends on many variables like the type of router, how it's configured, who's the ISP and even, when using a LTE modem, you need to consider CGNAT.

3CX just decided to stick to stuff that works: their SBC since it's client-side, STUN with port-forwarding, and local registration.

Otherwise, the Webclient/DesktopApp and mobile apps are the perfect way to use 3CX since they don't need any special configuration.