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Friday, November 20, 2015

Decoding T-Mobile's WiFi-Calling and VoLTE stats

A quick analytical post. I'm currently re-doing my WebRTC model for service provider use-cases, and as part of that I'm looking at data on adoption of VoLTE, WiFi-calling and other services/applications.

T-Mobile US is interesting as it's revealed various data-points over the past couple of years:
  • 2007 - original launch of UMA-based WiFi calling, notably on BlackBerry
  • May 2014 (link) - VoLTE launch, although the acquired MetroPCS had had a limited deployment since 2012
  • June 2014 (link) - 17m WiFi-calling enabled devices, with "almost 5m" WiFi calling users (including older UMA/GAN). The user base quoted is monthly average users (MAU)
  • July 2014 (link) - total of 52m VoLTE calls made
  • December 2014 (link) - 19.2m VoLTE calls per day & 6.6m WiFi calls per day
  • March 2015 (links here & here) -  7m WiFi calling users per month, 7.6m WiFi calls per day, 10% of calls on VoLTE
  • October 2015 (link) c12m WiFi calls per day
  • November 2015 (link) - a third of calls on VoLTE
Now, consider a few other data points. According to various surveys, a typical US mobile user makes/receives 6-7 calls per day. And T-Mobile had 61.2m subscribers at end-Q3.

That implies that T-Mobile US carries around 400m calls per day, assuming its users are fairly similar in usage pattern to AT&T & Verizon. (Note that the US quotes statistics including both inbound and outbound calls, in contrast to most other operators/countries which just count outbound)

In other words, only about 3% of T-Mobile's calls use WiFi calling. Put another way, VoLTE is 10x larger, despite being launched much more recently. And T-Mobile US has been by far the longest, largest proponent of WiFi calling, for more than 8 years, in both IMS and pre-IMS variants. The number is growing, as new devices support WiFi calling, but it's still a relatively small part of the total.

Also, looking at the user numbers, it seems probable that T-Mo is now on perhaps 10-11m MAUs for WiFi calling. But that's monthly - and those people collectively make more than 2 billion calls per month. So even among those users, only around 17% of calls are on WiFi - which makes sense as many will be using their phones outside their homes/offices.

To reconcile the numbers, it's probably better to think of perhaps 2m regular daily users, accounting for perhaps 8m calls per day, plus maybe another 8-9m per month whose phones switch to WiFi calling occasionally - perhaps in poor-coverage areas, or while travelling. The regular users will likely be those with poor coverage at home.

What does all this mean? In a nutshell, it suggests that WiFi calling is less of a big deal than many think - and is primarily a customer-retention tool for operators with in-building network limitations. It's not (currently) a meaningful source of voice traffic offload. 

3% of calls and 3% of subscribers as regular users, for the most-aggressive operator pushing the technology, is not hugely impressive. By contrast, the adoption of VoLTE has been surprisingly rapid, although the stats are possibly skewed a bit by high-end/telephony-heavy users.

It also implies that many operators may well not bother with full IMS-powered WiFi calling, instead taking a path towards using separate VoIP (or video) apps such as Orange Libon or Telefonica Tuenti Mobile. In particular, these "secondary" apps can offer a different experience to ordinary phone-calls from the native dialler, especially with WebRTC as a more flexible enabler/platform than IMS.

It's also worth noting that T-Mobile is starting to push its new 3G/4G small cell ("CellSpot") for people with poor coverage, which may mean that some users actually reduce their reliance on WiFi for calls at home or in small offices. (link)

Some of the comments I heard at yesterday's WiFi Now conference in Amsterdam seem over-hyped. I'm yet to be convinced that many enterprises will open up their private WiFi networks for carrier VoWiFi in large numbers, in particular.

So overall, I expect IMS-based WiFi calling to continue growing, especially in markets that have high numbers of calls-per-subscriber, plus variable-quality coverage indoors, or for operators with limited sub-1GHz coverage. Maybe, with Herculean and very expensive efforts, a few operators might reach the 10% mark for calls carried over WiFi. And that's only if they get all phones auto-provisioned, they work with enterprises and venues to integrate WiFi calling with in-house WiFi, and don't push hard on small cells or LTE-U.

Meanwhile, the overall market for "boring old phone calls" will continue to drop regardless. Yes, if WiFi-calling can be added cheaply and easily then it's a useful "maintenance" enhancement of legacy telephony. But it's not a substitute for (or component of) proper innovation around voice, video, WebRTC and contextual communiations. That needs to be the strategic priority, not window-dressing for a few percentage points on a decades-old service.

Disruptive Analysis publishes research & does private consulting/workshops, as well as conference speeches, on areas such as WiFi calling, VoLTE, WebRTC and next-generation voice/video/messaging applications. It has covered the convergence between WiFi and VoIP since 2003. Please contact information AT disruptive-analysis DOT com for more information.

1 comment:

Chris D said...

Dean, very interesting information gathering. Have you considered whether the quality of the T-Mobile WiFi calling may not be sufficient to keep users engaged?