Smoothwall help with SIP ALG

[snagrat]

I am supporting a school who have Airband internet and a S8 appliance.

 

I need to install some phones. The phones connect to an external PBX over 5060 and show as online but when they ring there is no voice.

 

Most firewalls have a simple way to disable SIP ALG but the Smoothwall seems more complicated. I think it is the ALG that is not allowing the voice.

 

Can anyone explain how I would do it?

 

I have 3 networks from what I can tell - internal, external and bridged.

[slugshead]

NEtwork > Settings > Advanced

 

Untick SIP

 

save

 

Reboot

[snagrat]

NEtwork > Settings > Advanced

 

Untick SIP

 

save

 

Reboot

 

Interesting. I was looking at the SIP Proxy settings section.

 

Didn’t even know that other setting was there. Will give it a go

[howartp]

We've spent several months fighting Smoothwall, Gamma (SIP provider), our two ISPs, and our telephony provider, and not managed to get SIPS working - similar scenario to you, rings but no voice, voice but no ring, pickup but no answer/termination when you hang up, ...

 

We've given up and moving to a VoIP solution instead.

[ibpalle]

We've spent several months fighting Smoothwall, Gamma (SIP provider), our two ISPs, and our telephony provider, and not managed to get SIPS working

 

You shouldn't need to fight the Smoothwall on this - the provider should give you the requirements for their solution on the firewall side. The SIP proxy and the SIP helper mentioned above is rarely required so definitely turn those off unless the provider says they are needed.

[howartp]

You shouldn't need to fight the Smoothwall on this - the provider should give you the requirements for their solution on the firewall side. The SIP proxy and the SIP helper mentioned above is rarely required so definitely turn those off unless the provider says they are needed.

 

Oh I get that - but when I plug our phone system into the router and give it a public IP, bypassing Smoothwall, many more parts of the SIP connection start working - not all, but many.

 

So either SIP, ALG, NATing, firewalling or something else in Smoothwall is having a significant impact on it, but Suraj and Tao assure me it's not our Smoothwall causing the issue.

[ibpalle]

All of those things affect SIP - what does the provider tell you is needed on the firewall? When you plug in the phone system to the Smoothwall, was the config on the phone system changed to allow for NAT e.g.? One issue with SIP is the source IP of the caller is included in the SIP package content and if that isn't change to the NAT IP on the phone system config, then SIP will fail as return traffic tries to go to the internal address of the phone system, which will never work. Did the provider tell you anything about port forwards?

 

It's not really unusual to have a NAT in place on the network and the provider should be able to tell you what is required when the system is behind a NAT.

[CrootUK]

We found on our SNAT if we were restricting it to certain ports on smoothwall it caused audio (RTP) issues even though every port was in there, once changed to all ports it fixed it.

[snagrat]

I have my three phones set to allow all ports to all destination, just the voice not working. Not even one way.

 

Will be turning off SIP complete tomorrow to see if it helps

[snagrat]

Turns out that turning SIP on in the Advance settings worked for me.

 

Thanks you for the suggestion to look there!

[slugshead]

Turns out that turning SIP on in the Advance settings worked for me.

 

Thanks you for the suggestion to look there!

 

Glad I could help

 

We've spent several months fighting Smoothwall, Gamma (SIP provider)

 

I'm using Gamme too. Port forward and a SNAT rule works fine. The Gamma docs do say a 1-1 NAT, which in Smoothwall terms is a Port Forward and a SNAT

 

Port forward

 

Client - Gamma IPs

Local IP - Whatever address you're setting from outside

Services - Voip (includes sip). I added the RTP ports to this rule too

Target IPs - your PBX

 

SNAT rules

 

Source - Your PBX

Destination - Gamma IPs

Services - VOIP and RTP

SNAT - Tick

Gateway - External IP which matches Local IP from above