VOIP Bandwidth and Download Limits

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aboylikedave

243 posts

Master Geek

#55377 1-Jan-2010 19:09

Hi guys, just moved to NZ, never used VOIP before. I hope this question isn't stupid, but since most broadband packages here have a download limit, how much does VOIP use? Enough to push you further to the limit?

Cheers

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sbiddle

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#286446 1-Jan-2010 19:57

What sort of VoIP are you talking about? Skype, SIP? If it's a SIP provider what codec do you plan to use?

And more importantly how often do you plan to talk for? If you're talking for an hour a month you'll be looking at somewhere in the vicinity of 25MB - 60MB in total. Talk for 20 hours per month and that'll be somewhere in the 500MB - 1.2GB range.

If you are with ISP's who offer a VoIP service such as Xnet then VoIP traffic to their own VoIP service does not use any data.

aboylikedave

243 posts

Master Geek

#286447 1-Jan-2010 20:11

sbiddle: What sort of VoIP are you talking about? Skype, SIP? If it's a SIP provider what codec do you plan to use?

And more importantly how often do you plan to talk for? If you're talking for an hour a month you'll be looking at somewhere in the vicinity of 25MB - 60MB in total. Talk for 20 hours per month and that'll be somewhere in the 500MB - 1.2GB range.

If you are with ISP's who offer a VoIP service such as Xnet then VoIP traffic to their own VoIP service does not use any data.

Hi. I'd heard 2Talk is good. Didn't know about codecs for SIP. Is there a sticky here about CODECs? I reckon about 5 hours a month SKype and the same by SIP. Do your figures apply to both skype and SIP? If they give me a good ballpark figure, thanks thats v useful.

My EPL football websites: Get the results but hide the score of your team at HidetheScore.net. Compare league positions with wage bills at RealPremierLeague.net.

kiwiscoota

237 posts

Master Geek

#286964 4-Jan-2010 19:12

aboylikedave:
sbiddle: What sort of VoIP are you talking about? Skype, SIP? If it's a SIP provider what codec do you plan to use?

And more importantly how often do you plan to talk for? If you're talking for an hour a month you'll be looking at somewhere in the vicinity of 25MB - 60MB in total. Talk for 20 hours per month and that'll be somewhere in the 500MB - 1.2GB range.

If you are with ISP's who offer a VoIP service such as Xnet then VoIP traffic to their own VoIP service does not use any data.

Hi. I'd heard 2Talk is good. Didn't know about codecs for SIP. Is there a sticky here about CODECs? I reckon about 5 hours a month SKype and the same by SIP. Do your figures apply to both skype and SIP? If they give me a good ballpark figure, thanks thats v useful.

Codecs are used for all internet voice and or video transmission to compress the data.

There's a calculator available at http://www.asteriskguru.com/tools/bandwidth_calculator.php

Using that calculator, you need to select
(1) Regular Audio Codecs then the Codec you wish to use, I use G711.
(2) You can ignore the Speex Audio Codec line
(3) Select SIP

Note that the data usage is quoted per second,

eg G711 : Total bandwidth (incoming and outgoing): 159.26 Kbps

I would expect Skype to use similar bandwidth.

sbiddle

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#286981 4-Jan-2010 20:14

kiwiscoota: Codecs are used for all internet voice and or video transmission to compress the data.

There's a calculator available at http://www.asteriskguru.com/tools/bandwidth_calculator.php

Using that calculator, you need to select
(1) Regular Audio Codecs then the Codec you wish to use, I use G711.
(2) You can ignore the Speex Audio Codec line
(3) Select SIP

Note that the data usage is quoted per second,

eg G711 : Total bandwidth (incoming and outgoing): 159.26 Kbps

I would expect Skype to use similar bandwidth.

Skype uses a lot less (assuming it's an audio only call). G711 is an uncompressed PCM codec so uses a lot of bandwidth. All new codecs offer some form of compression.

Skype usage is typically around 30kbps - 50kbps for an audio call, depending on the codec. Video will of course up that.

kiwiscoota

237 posts

Master Geek

#287001 4-Jan-2010 21:09

sbiddle:

Skype uses a lot less (assuming it's an audio only call). G711 is an uncompressed PCM codec so uses a lot of bandwidth. All new codecs offer some form of compression.

Skype usage is typically around 30kbps - 50kbps for an audio call, depending on the codec. Video will of course up that.

The G711 codec may not be as compressed as other codecs especially compared with some of the newer codecs BUT it is still compressed.

Specifically, G711 defines two main compression algorithms, the µ-law algorithm (used in North America & Japan) and A-law algorithm (used in Europe and the rest of the world), with G711 it's function is to compress 16 bit LPCM (Linear Pulse Code Modulated) data down to 8 bits of logarithmic data.

If any equipment uses a codec then it uses some form of compression algorithm.

The word "codec" stands for coder/decoder (and not compression/decompression as some might have thought) which in simple terms converts the analogue signal to digital for transmission.

Codecs are not exactly new technology, G711 first appeared in the early 70's and for many years before personal computing became popular, hardware codecs were (and still are) commonly used by broadcast radio & television stations to relay their audio & vision via ISDN, PSTN and satelite. The leading manufacture of hardware audio codecs was (and they still are considered market leaders) Musicam USA and their equipment set the standards that many others have followed.