Remote Extension without Port Forwarding

[snoop168]

Is there any way to hook up an IP phone on a remote network without requiring port forwarding or the use of a SBC? I am specifically using a YeaLink 42S. The SBC works fine for some sites but if I have a one-off employee that I don't want to walk through forwarding ports to use STUN, just didn't know if there was another option.

 

[Saqqara]

For locations with one phone you probably get away.setting up the phone as stun and not having to do portwarding, etc

this works most of the time, but all down to isp and router used

 

[cobaltit]

Is there a way? Absolutely, just plug it in. Is there a supported way? No.

 

[eddv123]

Is there any way to hook up an IP phone on a remote network without requiring port forwarding

Again as @cobaltit says there is no supported way, however I know that NATPASS SBC can provide such a solution: http://www.natpass.com/#section_3_wrapper

The configuration is performed on a cloud based SBC and on a custom template for the handsets. ABP Tech sell this solution: https://www.abptech.com/

Not suitable for a one-off deployment really (as it is a bit heavyweight) however something to think about if you see this issue occur more frequently.

 

[JohnS_3CX]

Hi @snoop168

We do not support using a STUN phone without the proper port assignments and forwarding for good reasons.

What you are describing is not impossible, but it is unreliable. If you can live with this trade-off then go ahead.

On the other hand, why not have your single user go on the mobile client or webclient? It should solve the problem altogether

 

[snoop168]

thanks @JohnS_3CX that was definitely a consideration, just didn't know what made the Mobile Client or Web Client work in basically the same scenario but a physical phone couldn't...

 

[JohnS_3CX]

Yes, unfortunately we cannot force the phones to use our tunnel (like mobile client does for example) but our SBC does that for you.

If SBC or apps/webclient are not an option for a specific user, then for best effort you will need to open ports for them on their modem/router, to make the STUN phone as reliable as possible.

 

[snoop168]

Thanks! I am just curious how another vendor's IP phones will work from a remote location without a SBC or Port forwarding. Not sure if it's technically still using STUN or if there are other methods/protocols that other vendors can use. Unless thats working the same way in the sense that its "unreliable" and we just haven't noticed the "unreliability" yet... That system happens to be a Tadiran using YeaLink phones if you happen to be familiar....

 

[JohnS_3CX]

The phones will generally work, you might never even notice an issue until someone points it out. The modem the customer has will remap the ports and allow audio and SIP to pass through. But after some inactivity, it might purge those ports and the next call might not come in until you make a call. Some other customer with a different modem may keep the ports open for longer, or only reuse them when needed. Others may handle it perfectly and you will always have perfect calls. There is no standard behavior on this though, and there are thousands of types of modems/routers one may come across. Others may block SIP altogether, or have some reserved ports and will not work at all. Others may have SIP ALG that cannot be disabled, and can break the SIP messages by rewriting the packets.

There are many unknowns out in the wild, so by making an effort to control them, you ensure reliability. That's the gist of it. How you implement a level of control can depend on the conditions (i.e. SBC, VPN, STUN+port forwards, use an app instead etc)

 

[cobaltit]

If this is the phone system you are talking about then yes, they have a SBC, it's just on the far end (provider's network) and not in the customer network.