Monday, July 13, 2009

How Much Bandwidth Does VoIP Use?

The dirty secret of VoIP is that while it enables calls that don’t cost much, it eats bandwidth that can cost a lot.

Bandwidth is the amount of data that computers can transmit through a wire or wireless channel each second. A single voice conversation requires a bandwidth of 64 kilobits per second for good call quality, so 64 kbps is the basis for discussing transmission speeds.

Despite technicians’ best efforts to compress voice signal size using algorithms you need a Ph.D. in math just to read, voice signals remain large. For your business to carry VoIP effectively and reliably, you need the appropriate computing firepower and a big-enough pipeline to handle VoIP call volume into, out of and around your network.

64 kbps is called digital signal zero, or DS0, and is not considered to be a high-speed line nowadays; the minimum for high-speed transmission is about 24 times faster than DS0, and is called DS1. This may be more familiar to you as a “T1” line. A dedicated T1 line is always on, transmitting and receiving the equivalent of 24 voice conversations from the Internet provider’s servers.

Businesses should consider a dedicated T1 connection as the minimum to support VoIP and other data traffic—but when that starts to feel cramped, upgrading to a DS3 line (or a fraction of one) should solve a company’s bandwidth problems for awhile.

Depending on your network and needs, you may be able to get by with a relatively low-bandwidth connection - but grow beyond a certain point and it may be time to upgrade to a DS3 line connection.

To ensure you get the right bandwidth solution for your VoIP network application .... you can put your mind at ease by taking advantage of the FREE assistance available through Business VoIP Solution.

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Blogger AC said...

64kbps may not necessarily be the required bandwidth for VoIP. It can also work on lower bandwidth, and depends upon which codec is being used. There's an article here, where some folks have done testing to find out:

1:33 PM  
Blogger jnelson said...

I agree with your synopsis that VoIP is not nearly as efficient as it is made out to be on paper. What you have not mentioned is that irregardless of which Codec you use 64kb or 8kb you need a big block of header information to enable the call to happen, typically around another 35kb of bandwidth making a 64kb call actually use 100k of bandwidth!
My company Voipex set out to solve this specific issue and have done so enabling calls to be made at the actual bandwidth the Codec intended + a very small amount of overhead. G711 uses 64kb and G729 uses 8kb. The latter when using ViBE our product is perfectly acceptable and useable for business grade calls (i.e. as good if not better than the standard mobile on a good signal) If that is not good enough then there are Codec's in between G.729 and G.711 which are more efficient.
In addition though ViBE delivers Encryption capabilities, Real Time Stats and reporting on the link being used (Jitter, latency calls in progress etc), The ability to bond multiple bandwidths together , QOS delivered at a more granular level than other products ensuring whatever other applications are running on the line do not affect the Voice quality at all. In addition because of the above features we can normally deliver up to 500% more traffic over a link than otherwise possible with VoIP, due to our accelleration and QOS.
Please fire any questions at me for more detail.

5:52 AM  

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