TestYourVoIP.com uses a software model based on an international telephony standard called the E-Model the ITU-T G.107 standard to be exact. While the theoretical MOS scale tops out at 5.0, you won't get a 5.0 score no matter how reliable your network connection is. That's because VoIP codecs introduce some amount of quality loss. For example, the maximum MOS score you can achieve with the quality-preserving G.711 codec is 4.4. For the low-bandwidth G.729 codec, the maximum is only 4.2.

TestYourVoIP.com will make a call from wherever you are to one of their U.S. or international test locations and report the results. Click here for you MOS score.

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