RVO42 and SIP Application Layer Gateway -Can it be disabled?

[stevenaddis]

We use a phone system that requires SIP Application Layer Gateway to be disabled on the router.  We replaced the older RVO42 routers with the WRVS4400N routers and the VOIP phone works fine with this checkmark option disabled.

Does the new RVO42 router allow you to disable this option?  I did not find it in the manual so far.  I do not want to buy two routers and find that it will not work with the phone system.  We need Dual WAN this time so I thought we would try RVO42 model again as long as it is the latest version.

Has anyone had any issues with newer RV042, RVO82 with NEC VOIP phone systems?

Thank you for any help.

[Te-Kai Liu · Accepted solution]

RV042/RV082 does not support SIP ALG, thus no conifguration option for disabling.

[stevenaddis]

Thank you for the response.  Do you have another Dual WAN router that support this feature? 

I actually never understood why the older RVO42 would not allow the VOIP to work over VPN.  It only partually worked and we simply replaced the router with a WRVS4400 and all worked fine.  RV042 did not have the disable option.

I would assume that we need a router that supports SIP ALG to disable so our NEC VOIP phone system will work. 

Thank you.

[Te-Kai Liu]

SA520 is a dual-wan security appliance that has a SIP ALG, which can be enabled/disabled.

[matt.siegel.cisco]

Does this mean that the RV042 does not support the use of VOIP phones at all?

[Te-Kai Liu]

If you have VoIP phones in the LAN of RV042, you could use Port Forwarding to forward the SIP traffic to the phones.

[matt.siegel.cisco]

How would you do that with mutliple phones on a LAN?  Also, doesn't that open up a hole in the firewall?

[Te-Kai Liu]

A single port range forwarding rule can forward SIP protocol to multiple devices in the LAN.

https://supportforums.cisco.com/message/3684143#3684143

[stevenaddis]

I find this article interesting.  I do not understand what this means. The "+x" number allows you to create one port forward to a range of IP's.

Because the phones are connecting to the phone system over VPN and not the Internet, I do not know how port forwards would affect somthing in the VPN tunnel.  It would seem you would need to have the phones hit the external router static WAN IP to do the forward which is a completely different phone configuration. 

Also, the phones would need strong passwords.

Such as port 1000 to ip 192.168.16.10+49 format covers all the IP's in the range?

You wrote...

For example, say you want to forward port X to a device with a private IP address of Y with a range of 50. A single port range forwarding (with range = 50) can forward

Port X to Y

Port X+1 to Y+1

Port X+2 to Y+2

...

Port X+49 to Y+49.

[Te-Kai Liu]

If the phones and SIP Server are reachable through a site-to-site tunnel, there is no need for Port Forwarding or Port Range Forwarding. Forwarding is needed only when SIP Server is on the internet, while the phones are in the LAN of RV042.

[stevenaddis]

This makes sense.

I looked at many of the lower end models that my customer needs and some support SIP and some do not. Th RV120 does just like the WRVS4400N which is end of life.  The RV180W does support SIP.  The RV110W (black boxes) do not.  I guess it will be standard in a while as the old models are phased out of production.  I wish firmware could add this features.  Not all of the routers supprt PPTP either and I found out that after the fact with the WRVS4400N.  The client you provide gets disconnected when the second person tries to connect.

So far the WRVS4400N works fine with the phone systems we use.  I would be sure that anyone that is going to use NEC VOIP phones over VPN to avoid the RVOxx series and be sure there is a SIP Application Layer Gateway option to disable when needed.

Thanks for your help.

[Bertil Blomskold]

I have replaced a cheap 30$ router with RV082, and after that ip-telephone do not work. Our external ip-telephone provider requires SIP Alg to be turned off, this was done in the old router, and since it is not supported in RV082 there is nothing to turn off - so it should work.

If I uncerstand correctly, that is the same as it is said above: "I actually never understood why the older RVO42 would not allow the VOIP  to work over VPN.  It only partually worked and we simply replaced the  router with a WRVS4400 and all worked fine." 

I am not using VPN by the way.

Even if I do not understand the logick why Port Forwarding then should help, I have tried to configure it as suggested - without any success either.

So what is then the problem with RV082??

[sraguraam]

In RV042 SIP ALG option is available in hidden page.Use the below link to access the hidden page of RV042 to disable the SIP ALG option.

https://192.168.1.1/f_general_hidden.htm