After several days of testing different locations a few trends were discovered that affected the call quality on our VOIP system.
In the graph below the MOS scores were averaged together at each location to give the average difference between locations over the course of 6 days.
- LTE reigns supreme
- Except for a single case, LTE is the superior network
- Location does in fact play a role in the quality of the call and affects all three networks relatively equally
- Notice how the MOS for all the networks rise and fall together depending on location
Location plays a role in call quality, now what about the day?
The graph below shows the MOS scores averaged across the 8 locations for each day.
Note: For 12-Sep Wifi was only tested at one location Yotsuya-thus the high score is a slight outlier.
Also note: Mori Building and Toranomon were only tested once, however, the locations were relatively consistent across the days.
As seen from this graph the day the cell phone test was conducted has an influence on the overall MOS score for all three networks. It can be observed all three rise and fall together depending on the day, and thus most likely from weather and traffic use variations across said days.
It can also be observed that LTE is the better network (September 12 is an exception as Wifi was only tested at one location Yotsuya and had a fluke high score this day as the Wifi was generally not as high here).
*Days 8/8, 8/9, 8/12 were grouped together as these were the first days of testing and not every location was tested each day and thus it was easier to combine. However that is also most likely the reason for the wider separation between the 3 networks.
If broken down the 8/8-8/12 days are as follows:
* On days 8/8 and 8/12 only 1 Wifi location was tested Yotsuya and Prudential Towers respectively:
- Thus the reason for their higher score.
- Illustrates that in general, while Wifi is the worst network if the Wifi network is strong (ie. a business or hotel Wifi) the PBXL VOIP client can still perform well.
Even if these three days (8/8-8/12) are ignored and one only looks at testing from 8/13 to 9/12 the conclusions made above in regards to LTE being the better network and the affect that the day has on the scores still holds true.
So what does this mean?
–Location Location Location-it matters: signal strength varies depending on your location for many reasons:
-distance to a cell tower
-background noise levels
-The Day matters…why? For many of the same reasons location matters:
-different traffic levels depending on time of day and day itself
-weather varies day by day and can influence network strength
-different environmental factors
- Location Averaging is the stronger method to analyze the VOIP quality:
Averaging days together for each location naturally evens out slight testing differences i.e. time differences, background noise level differences, and thus allows for better comparison across networks.
- Day Averaging is useful, however, to see how the networks themselves can change regardless of location depending on the day.
- By using both Location and Day averaging it is possible to see more clearly (and reliably) the networks’ performance, and from this analysis we can see:
- PBXL VOIP works with iPhone5 across all networks but performs best on LTE