What codecs does Voipfone support

#1
About Codecs

This article was originally from 2006, however we've updated in January 2014 to reflect the codecs available on our platform.

Since voice and sound are analogue, they need to be converted (or encoded) to a digital format suitable for transmission over the Internet. A codec is an algorithm used to do this job; it encodes and decodes a voice conversation.

We've updated this article for 2014, to reflect the best codecs to use on our platform.

There are a variety of different ways this encoding and decoding can be done - many of which utilise compression in order to reduce the required bandwidth of the conversation. Reducing the bandwidth will reduce the quality of the call somewhat but will enable you to squeeze more simultaneous conversations down the same connection. Getting this trade off right is up to you!

A key thing to remember is that encoding, particularly when high compression is used, takes time, which adds a delay to the conversation. The best codec is one that has good quality with compression, but is able to do the encoding and decoding in a minimal amount of time.

All VoIP telephones, both softphones and VoIP telephones and adapters, use codecs and unless you specify which one it will use the default codec. When you call someone their phone detects which codec is in use and applies its own codec automatically.

Voipfone supports the following codecs.

1. G.711(A) (High Quality)
This is a high quality codec providing CD quality (64kb) if used end to end. It uses a nominal 87.2 kbs of bandwidth (64kbs plus overhead) but requires at least 128kbs in both directions making it a relatively high bandwidth user.

2. PCMA (High Quality)
Also a high quality codec providing CD quality (64kb) if used end to end. It uses a nominal 87.2 kbs of bandwidth (64kbs plus overhead) but requires at least 128kbs in both directions making it a relatively high bandwidth user.

3. G.726-32 (Low Bandwidth)
In theory this is a good, relatively low bandwidth codec but in real life use it often produces low quality sound. Try it and see if it works for you.

4. GSM (Low Bandwidth)
Same encoding as used in GSM mobile phones (though improved versions are often used nowadays). So expect the same sort of voice quality. Very low bandwidth use 13kbs (plus overhead)

Feel free to try each to find how they work for you; generally speaking we recommend G.711a.
Regards,

Voipfone Customer Services

iNet Telecoms Ltd (Voipfone)
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United Kingdom

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Telephone: 020 7043 5555
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