atcomsystems.ca/forum Forums VOIP Phones & IP PBX VoIP & Cloud Phones, Hosted PBX, General IP Phones Help! Can't network system anymore!

We have a customer using two Vodavi XTSc systems that have been networked using VoIP for over a year. One is on the North end of town and the other is on the South end. Both sites are connected using cable modem service with the same cable TV provider (Cox).

We relocated the system that was at the South end to a new location right across the street from the original one. The cable people set them up with a new modem, new IP addresses, etc. We reconfigured both switches to accommodate but they won't talk anymore.

We can ping the IP card in both switches from outside just fine. The problem we have found is that both sites are now on the same gateway and subnet. According to Vodavi, this won't work because the systems can't be on the same subnet. They "know" that the IP is in the same subnet so it doesn't try to go out over the Internet. They claim that we must either have Cox place the second location on a different subnet or switch to another ISP at the second site to ensure a different gateway for each site.

Cox won't do this because there is penty of space left in the current subnet and they aren't going to open one up just for us. There's been talk of "bridges" being installed to accommodate this, but again, Cox won't have any part of it.

I don't know who to believe now. None of it makes any sense to me, but then, I am not very savvy when it comes to this stuff. All I know is that when the IP's were 68.XXX.XXX.XXX and 24.XXX.XXX.XXX, everything worked fine. Now everything is 24.XXX.XXX.XXX at both ends with the same subnet.

Can anybody help? The customer is not going to pay for additional hardware, nor are they going to switch to another ISP at one side. We quoted them a firm, fixed price to relocate the system assuming that this would be a piece of cake.

Can't you assign different static IP's to the network cards and have the node pointed to the hub??

This would be the same as all PC'S on the same domain.

And since your two sites are now on the same gateway and subnet there is no need to go outside the infrastructure and hit the IP cloud, thus it is now intranet and not internet.

We do have different static IP's for each network card. It's the fact that these IP's are in the same subnet that is apparently causing the problem.

I'm thinking a cheap cable router/firewall (netgear or linksys) on one side of the connection. That system gets a 192.168.x.x subnet (with a completely different subnet mask too - 255.255.255.0). Then in the firewall, set the DMZ (De-Militarized Zone - basically unrestricted incoming traffic) address to the system's address.

Thanks, Rob. I agree with you on that, but the systems don't currently work in a NAT environment; everything must be full public IP addresses. So far, the cable company can't understand this limitation, nor can I. It's more frustrating to me because I don't know enough about it to have any influence.

What about setting the gateway for each of the systems to be the other systems ip address?. SO for example if the systems are 192.168.1.100 and .101 and you are currently using .1 as the gateway switch it to .100 or .101. If the system doesn't find the other one it should look to the gateway address and find the other system there.

I would have thought Rob was right. Have you tried to put a router in front of one of the systems just to see what it would do Ed?

Both systems are connected directly to the cable modem; there is no router involved so we are relying upon the ISP as the gateway. Like I said, we just moved the existing equipment and didn't add or change much of anything except the IP address for the new site.

I get you. But what Rob is saying is that you can connect a router to the cable modem with the static ip address from the isp, then change the ip address going to the system so that is in another ip scope.

Ed,
Are they using any VoIP phones outside of the building?

Larry