The T-Mobile WiFi calling feature came to iPhone users with the iPhone 6. It’s actually a well-refined feature that has been on the T-Mobile network for years, and this seasoned and stable feature shows refinement.
Our experience with Verizon Advanced Calling 1.0 has been simply terrible, with poor audio quality and frequent dropped calls along with limited coverage inside of buildings. Perhaps they should have taken a lesson from T-Mobile and should have offered WiFi calling.
When you think about it, WiFi calling makes sense. When your phone is in range of high-speed Internet and a WiFi hub why not route the voice over that channel. Not only will you have excellent indoor coverage but you will off-load expensive towers from this voice traffic. Good voice quality right where you need it is what WiFi calling is all about.
WiFi calls are of excellent quality, with crisp clear connections. On T-Mobile the startlingly good audio quality isn’t as noticeable since T-Mobile also enabled HD Audio on their GSM network. So you go from great quality to excellent quality on WiFi. (Contrast that with Verizon which has poor audio quality on their CDMA network and frequently terrible audio quality with their VoLTE Advanced Calling 1.0 product.)
T-Mobile’s pricing is killer good. Aside from their bundling free unlimited international data with their Simple Choice plan they seem to always side on good engineering and WiFi calling is just one example.
There is one Gotcha that was totally unexpected with T-Mobile’s WiFi calling and you should be aware of it. WiFi calls are treated as if they originated in the United States, no matter where you actually are.
This means that if you are in Beijing and are calling somebody in Beijing you are NOT billed T-Mobile’s very reasonable 20-cent per minute global roaming rate. You will be billed $1.99 a minute or ten-times more! Yes, if you use T-Mobile WiFi calling while overseas you will pay terrible unreasonable rates.
You can overcome this oddity by subscribing to their Stateside International Talk program for a flat $10 a month. Then, calls are either free or are 20-cents a minute on both WiFi and GSM. Another option is to disable WiFi calling when traveling internationally.
It was unexpected that WiFi calling would substantially increase the cost of international roaming calls, so you will want to keep this in mind.
But the great news is that with WiFi calling you get good indoors coverage even where T-0Mobile may have no coverage…such as in rural areas.