Using something called the Mean Opinion Score (MOS) we are able to determine with a measure of accuracy voice quality over varying connectivity methods. To establish a MOS, listeners (in the case of the study I am quoting 30 to 50 people) listen to speakers of both sexes read specific sentences. Each listener then rates each sentence as follows: (1) bad; (2) poor; (3) fair; (4) good; (5) excellent. The arithmetic mean of the individual scores is the MOS. The International Telecommunication Union (ITU) endorses this testing method. Here are some of the suggested sentences:
- You will have to be very quiet.
- There was nothing to be seen.
- They worshiped wooden idols.
- I want a minute with the inspector.
- Did he need any money?
On a scale of 1-5 where 5 is excellent, VoIP with a G.711 codec and a long distance toll call come out equal with 4.4 each. Even the G.729a codec beats a cell phone call with 4.2 versus 3.8.
Software tools have been developed that automate MOS testing. These tools do a better job of evaluating network conditions and codecs more consistently than human listeners.
So, inform your prospects and customers that VoIP/SIP Trunking is as good as your current phone service and with Broadvox and other ITSPs, you can save up to 70%.
Enjoy the Holiday. See you on Wednesday.