Remote phones lose registration

I have a system behind a Cisco RV042 router. There is port forwarding setup for ports 5060, 10000 -20000. I have two distant offices that have remote phones. They are on cable connections, both static IP addresses. I can get the phones to register and work, but after what seems to be a random time they become unreachable from the system, according to the SIP Info report. When I try to call them I get the voicemail Unavail greeting. The larger of the small offices (4 phones) has a Linksys BEFSR41 router. The other office router is unknown at this point. I do not have direct access to the Cisco router, but I do have access to the guy who does. Can someone help me out here?? I have never had this much of an issue with setting up remote phones. I know that I should be using VPN’s but that isn’t possible at the moment.

Thanks for any suggestions

Many things conspire to make SIP remote endpoints a challenge.

What is the barrier to using a VPN? It simplifies the process greatly.

I just brought this up to the IT guy. The customer had some bad IT in the past and they are reluctant to go back. Just for grins we have ALL ports forwarded to the system and we still have the Unreachable in the report randomly. Is there a registration timer that maybe is set to short for this??

There is more to it than port forwarding. I would be more interested in if you have some type of ALG for SIP enabled in one end or the other.

Your firewall may be closing ports on the fly.

You didn’t answer my question regarding VPN’s


They will not think of a VPN at this point. I did however find out that the Cisco RV024 has sip alg embedded and no way to turn it off. We will be putting in a DD-WRT router tomorrow.

“They will not think of a VPN at this point”

I don’t want to beat a horse but I just don’t get it. It’s like they are saying, we won’t use something that we know will work and we will screw around with the less reliable and insecure method.

I don’t get it. You already have a VPN router.

I know and I will try again to get them to setup a VPN. Just getting them to replace the router is a big step. Would the SIP ALG in this router apply when the SIP is running over the VPN?

No, it would not. ALG works when going from trusted to untrusted zones. VPN’s are layer 2 connections that bridge two LAN’s

I will be installing two new routers at the remote sites. Then they will all be the same. Then I will lobby for a VPN. I have to take small steps with this customer. The IT guy does not like change. Plus there is alot of politics involved because they are our company Accountant.