Using Mobile VoIP over WiFi
WiFi was originally designed for data communications and using it for voice has a number of issues.
(1) Log on and Authentication
Once you find a suitable WiFi network you may have to log on and be authenticated to make use of it. Log on and authentication can be time consuming and tedious especially with a mobile phone key pad to enter user names and passwords. The detailed process is likely to vary from one WiFi network operator to another.
It is a big advantage if your Mobile VoIP provider has agreements with public hotspot operators which enable you to easily log on and use those operators hotspots or is making use of standardised log on processes.
Log on and authentication in the home or office is much less an issue as you can configure your phone to use those WiFi networks in a one-time set-up process
(2) Mobile Phone Battery Life
WiFi radio procedures and interfaces are designed for data devices which have more power available than handheld device like mobile phones. When logged on to a WiFi radio a mobile phone is more active than it would otherwise be and the battery power is used up more quickly.
One service provider states that stand-by battery life on WiFi is half that on cellular. Instead of four days the battery would last two days. Talk time remains the same or slightly improved.
Work is underway to develop technologies which will preserve power during voice over WiFi communications and improve battery life.
(3) Quality (range, coverage within hotspots, WiFi network voice call capacity, interference)
For data applications the range of single WiFi network can be as much as 100 metres but bad siting, problem obstacles, and interference can cut it down to as little as 10 metres. Also, a mobile phone is likely to have half or less the range of a laptop as it has a significantly smaller aerial.
Capacity should not be a limitation.
Interference may interrupt or prevent calls. Sources of interference include, appliances (such as microwave ovens found in homes and offices), toys, other types of phones, Bluetooth devices, other nearby WiFi networks, and even people walking close by.
The Known Issues page on one Voice over WiFi provider's website refers to interference form physical obstructions including someone walking between the mobile phone and the WiFi access point.
(4) The Potential for Using WiFi
Statistics illustrate the potential of voice over WiFi. Various sources quote the following: 65% of mobile calling minutes are generated from the home or office; 30% of mobile calls are made indoors; and more than 50% of employees' mobile phone calls are made within offices.
They all say something slightly different but what ever the best way of expressing this information there is a very large slice of mobile calling when a WiFi hotspot would be useful.