Is Your Internet Connection Fast Enough for VoIP?
Are you thinking of ditching your old wireline telephone and going exclusively with a Voice over Internet Protocol (VoIP) telephone, sometimes called an Internet phone? Your Internet service provider needs to meet certain requirements. One is raw bandwidth--the carrying power of your uplink and downlink. Be careful here--often what is advertised is the downlink speed--sometimes the uplink speed is much slower.
An Internet phone will require about 90 Kbps (kilo bits per second) both up and down. If your broadband link is faster than this, you may be ok on the bandwidth front. But note--if your link isn't much faster, and another person in your household who is sharing the line with you starts a download, for example a song for an iPod, this can cause voice quality issues, including stuttering and occasionally completely dropping the call.
But there's more. In addition to measuring bandwidth, one also needs to know the latency. The latency is how long it
An Internet phone will require about 90 Kbps (kilo bits per second) both up and down. If your broadband link is faster than this, you may be ok on the bandwidth front. But note--if your link isn't much faster, and another person in your household who is sharing the line with you starts a download, for example a song for an iPod, this can cause voice quality issues, including stuttering and occasionally completely dropping the call.
But there's more. In addition to measuring bandwidth, one also needs to know the latency. The latency is how long it
takes to get a packet (a small piece of information--the basic package carried on the Internet) to get from your place to wherever the VoIP provider's servers are. There are a number of ways to do this. If you're brave, you can use the Command Line in Windows. To do this, click Start, then click Run, type the letters "cmd" (without the quotes), and press enter. Then, at the prompt (which ends in a greater-than sign -- >) type the letters "ping" followed by a space, followed by the name of some website, for example, www.yahoo.com. You'll get four lines of information back. The screen will look something like this:
Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.
C:\Documents and Settings\Administrator>ping www.yahoo.com
Pinging www.yahoo-ht3.akadns.net [209.191.93.52] with 32 bytes of data:
Reply from 209.191.93.52: bytes=32 time=88ms TTL=57
Reply from 209.191.93.52: bytes=32 time=123ms TTL=57
Reply from 209.191.93.52: bytes=32 time=98ms TTL=57
Reply from 209.191.93.52: bytes=32 time=130ms TTL=57
Ping statistics for 209.191.93.52:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 88ms, Maximum = 130ms, Average = 109ms
C:\Documents and Settings\Administrator>
What you're looking at is the "time" variable. This lists how long it took for your computer to talk with Yahoo's server and then for Yahoo's server to talk back to your computer. It's measured in milliseconds (thousandths of a second). In the example above, those times vary quite a bit. If they're too long, VoIP won't work.
There's an easier way. Simply go to http://www.testyourvoip.com and perform the test. This site measures quite a variety of qualities and gives you a general score.
Try it out and see! The test is not perfect, but it's interesting information. Where did I find out about this link? From my VoIP provider, AT&T Callvantage.
