When all your devices on your LAN (local area network) are sharing an Internet connection on the WAN (wide area network) side of the router, the router WAN port becomes a potential bottleneck through which all devices on the LAN side are routed through.
Let's consider why the WAN side of the router is potentially a bottleneck.
- Your WAN side Internet service connection can range anywhere from ~ 256 Kbps to 100+ Mbps (download), while your upload speed may only range from ~ 125 Kbps to 5+ Mbps, depending on your location and service provider (ISP) package.
- Ethernet cards and devices, on your LAN, are typically rated at 10, 100, or 1000 Mbps (or auto-detect). This is typically much faster than than what your Internet WAN side can handle (or allows).
Now, lets consider downloading Windows XP Service Pack 3 (~ 316 MB) , or some other huge file... and, then your VoIP ATA, or softphone, rings and you answer the call.
If you happen to be subscribed to Internet service that only allows 1Mbps download and 256 Kbps upload, there is going to be some serious data bottlenecking through your router WAN port.
The solution here is:
- Make sure your router has built-in QOS functionality, and that it is Enabled.
- If your router doesn't have QOS, get a new router that does.
Remember, VoIP is "real-time" data... and it has to be the first packets through the pipe... otherwise, you will be complaining about how bad your VoiP service is. QOS will give your VoIP packets the high priority they need to pass through your router in first class...