Choosing Codec for Voip / SIP

Yesterday I did some tests calling myself using voip call to mobile phone (using zoiper over 4G) and I was horrified.

It was very annoying to hear myself :o)

So I decided to do a more thorough analysis of quality over different conditions (sometimes when you call to very distant countries the overall network quality degrades, and so the quality of the voice, so you need a more resilient codec).

Today I put my phone on 2G (4G is too nice) and performed different experiments with

G.711

iLBC

GSM

Then I compared my results with other tables out there (a nice one here https://www.gl.com/voice-codecs.html)

Here is a summary from that page

I decided to take out G.711 which behaves bad when the network has 'issues'. Supervoip (betamax) seems not to support Speex so the comparison was mainly with the other 2.

Finally I have decided to set up the codecs in this order (within Zoiper):

1. iLBC

2. GSM

3. aLaw (G.711)

4. Speex (just in case)

5. uLaw (because I rarely am in USA/Japan)

I must say that I hear very well most of the time, but the other part not so well with farther calls (I was using aLaw as first, but not anymore).