VoIP Bandwidth
I am trying to figure out the necessary bandwidth for good quality VoIP calls. The situation is our company has International branches that use IP phones and in some areas (ie. Countries in Africa) the QoS is poor. These countries only use 1 IP phone. I do not know their bandwidth/ISP situation, but I do understand it relies heavily on available/dedicated bandwidth.
What I need is a general overall guidance of the bandwidth needed per IP Phone connection (ie. 100 kbps) and some of the factors that can deteriorate the QoS (ie. weather, equipment, web browsing etc.). I also need to pass this info to non-technical people so they will know what they have/can do to improve IP voice calls.
We will be improving our Voice communications sometime in the new year, but I need an interim solution.
Thanks.
What I need is a general overall guidance of the bandwidth needed per IP Phone connection (ie. 100 kbps) and some of the factors that can deteriorate the QoS (ie. weather, equipment, web browsing etc.). I also need to pass this info to non-technical people so they will know what they have/can do to improve IP voice calls.
We will be improving our Voice communications sometime in the new year, but I need an interim solution.
Thanks.
Lazarus
Here is a handy link to figure out your VOIP Bandwidth: http://www.bandcalc.com/
Most IP phones support the G.729 codec and it uses considerably less bandwidth than the standard uncompressed G.711 A-Law/u-Law. However, you need to check that G.729 is supported by the equipment at the other end. For example, if using Asterisk, you need to purchase a license for G.729 and install it on the Asterisk server.
Internet connections are often asymmetric - i.e. they provide more download bandwidth than upload. VoIP useage is symmetric so don't make the mistake of only looking at download bandwidth/speed. Web browsing over the same Internet line as you are using for voice would therefore have less impact than uploading a large file. However, it is always best to avoid simultaneous shared use of a low speed Internet connection for both data and voice. VoIP speech quality over an Internet connection may be influenced by factors beyond shared use within your own location because there is usually some wider sharing of equipment further upstream - e.g. you will see reduced access speed when other subscribers are accessing the Internet.
An alternative to the very handy bandwidth calculator suggested by lazarus98, is this comparison table:
http://www.ozvoip.com/voip-codecs/
Internet connections are often asymmetric - i.e. they provide more download bandwidth than upload. VoIP useage is symmetric so don't make the mistake of only looking at download bandwidth/speed. Web browsing over the same Internet line as you are using for voice would therefore have less impact than uploading a large file. However, it is always best to avoid simultaneous shared use of a low speed Internet connection for both data and voice. VoIP speech quality over an Internet connection may be influenced by factors beyond shared use within your own location because there is usually some wider sharing of equipment further upstream - e.g. you will see reduced access speed when other subscribers are accessing the Internet.
An alternative to the very handy bandwidth calculator suggested by lazarus98, is this comparison table:
http://www.ozvoip.com/voip-codecs/
ASKER
So feptias are you suggesting for example that 100 kbps for 1 voice connection may only be the download speed? And that it will require double that? Or that 100 kbps is for symmetric usage (50up/50down)? I am asked to throw out a number '384 kbps' that is needed for voip. I am not sure where this number came from and if it included the factors you mentioned and that I have found in my research.
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ASKER
lazarus98 - is that 98k total bandwidth (both ways)?
The bandwidth requirements are each way. So if you are using the G.711 codec it will need 72kbps upload and another 72kbps download. However, Internet service providers usually quote the download speed - they do not add their max download and upload speeds together so you don't need to add them together when you are comparing.
The 90Kbps is for both, yes.
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