Oh was this about phones? Oops
Wifi can be used for internet and phones and tv and movies.
I am signing up for T-Mobiles $30 plan (google that to find it at the T-Mobile site and bring your own phone) and will get 5gb per month 4g download and then slower 3g if I use the 4g up before the month is over.
I only get 100 minutes of talk but if you use wifi for voice or an app you can use the internet for the voice call. It is 1mb to 3mb per minute.
I see the price coming down for getting internet & phone & video because of the higher speeds as people will dump cable and pick ala carte the shows they want.