why can't I hook two ip phones to a switch and router and talk across them? I don't want to go to the internet or to a public phone system. Just make ip phone calls on a closed network across two routers. People tell me I need special routers to do this. why???? an ip packet is an ip packet right?
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The comment about special routers may be in reference to having QOS abilities on the network (Quality Of Service). You are right that an ip pack is an ip packet but this can cause problems for ip telephoney because phone traffic is sensitive to packet loss and unstable latency. So QOS can give SIP packets a higher priority than the other traffic. On a busy network this can make a big difference in call quality.
I missed the part about router to router on a internal network. The direct IP calling is probably not going to get through the routers.
The 'special' routers are voip enabled - what these do is detect the type of traffic and open/close the appropriate ports etc. The problem is that IP phone traffic involves multiple ports and the range is fairly wide, so if your routers do not have special functionality it can be a bit of a mess to get calls to pass through them properly.
Here's a article that outlines the problem and some solutions,
http://www.voip-info.org/w
If you like to try out what VoIP does over your network setup, try SJPhone (http://www.sjlabs.com/), it's a softphone that can do IP to IP calls (SIP only I believe).
I was given a cisco router with a dual vic card in it. what hooks into these ports. Since I have no intention of hooking to a pst or going out on the internet to make phone calls. I still do not understand why everone says I need this card. All I want to do is ip phone calls on a closed network.
I will try the sip software phone as soon as I get a usb mike.
gair
http://www.cisco.com/en/US
Scroll down to figure 2 (sample voip network) This gives you an example of analog (normal everyday) phone, connected to a router and calling a remote site with a router and analog phones. The document itself shows you how to setup a simple network for phone to phone calls. Notice that one end of this network could be a router without "phone" ports, but a voip phone or softphone instead. sjphone works well for testing with the router and analog phones.
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by: kode99Posted on 2007-07-31 at 23:28:36ID: 19606617
You can make calls directly between two ip phones on your own network. It certainly is not impossible but I believe that not all phones will have the ability to place direct calls. So if you have some phones check the manuals.
Grandstream phones and ATA's offer the ability to direct dial IP addresses to connect calls. Here's the instructions,
http://www.grandstream.com
QTelnet actually markets a 'freeride' product line for doing this,
http://www.qtelnet.com/pro
You can usually also do this with ATA adapters. So connect two plain analog phones with ATA's where you pick up one phone and it rings the other - hotline type service.
I've never heard of QTelnet before but Grandstream is a fairly popular manufacturer of budget priced IP phones.