All codecs offer some kind of compromise between sound quality (which is a rather subjective attribute) and resources used (bandwidth and processing power). The best codec for you may not necessarily be the best for your conversation partner.

Most people find that the most natural sounding voice is provided by G.711u, also known as u-law, μ-law or pcmu. However, you can still maintain an pretty good voice quality and lower bandwidth usage with codecs like G.729. Note that GSM has the worst voice quality but offers the best bandwidth savings. If you specifically require it, please let us know.

Codecs such as GSM and G.711u are usually provided for free in free softphones, but G.729 may be available only at extra cost due to licensing issues. Since it uses more bandwidth than the free GSM while providing only a negligible improvement in voice quality, we recommend you do not use G.729. If bandwidth is not a concern (and with most modern computers or Data plans it is not), we recommend you disable all codecs except G.711u (or ulaw).