AT&T measures data traffic growth in multiple ways

Timed to coincide with the release of Cisco's annual report on mobile data traffic, AT&T Mobility (NYSE:T) reported Tuesday that its wireless data traffic doubled in 2011. However, at recent investor conferences, AT&T executives said that data growth was increasing at 40 percent annually.

How to reconcile the two seemingly contradictory figures? AT&T argues that both the 100 percent growth and 40 percent figures can be accurate because it's measuring two different things.

"Running year-end numbers that show the same result as previous years is typically a sign of stability. But when the year-end numbers show a doubling of wireless data traffic from 2010 to 2011--and you've seen at least a doubling every year since 2007--the implications are profound," John Donovan, AT&T's senior executive vice president of technology and network operations, wrote in a blog post Tuesday. "Over the past five years, AT&T's wireless data traffic has grown 20,000 percent."

According to the Wall Street Journal, AT&T said that the 40 percent figure represents only the increased usage from existing smartphone users. AT&T executives have recently used the 40 percent growth figure when discussing the company's move in January to increase its smartphone data pricing (along with the limits of its usage tiers). However, when AT&T adds in increased usage from new smartphone and other data users, the growth jumps to 100 percent annually.

AT&T has repeatedly used its growing data traffic figures to justify its calls for getting more spectrum. The company's growing data usage was a chief argument AT&T marshaled before regulators in its ultimately unsuccessful bid to acquire T-Mobile USA.

Another factor that could be at play is whether AT&T is including Wi-Fi offload data traffic in its estimate of overall traffic growth. In the past, AT&T has referred to growth in "mobile data," but Donovan's blog post refers to "wireless data." According to calculations by TMF Associates analyst Tim Farrar, AT&T's Wi-Fi offloading traffic grew from around 20 percent of all wireless traffic at the end of 2010 to around 30 percent at the end of 2011, which would ease the overall on-network cellular data traffic growth to around 75 percent annually. 

For more:
- see this AT&T blog post
- see this GigaOM post
- see this WSJ article (sub. req.)
- see this TMF Associates post

Related Articles:
AT&T increases pricing, usage thresholds on smartphone data plans
Study: Top 1% of global users generate half of all mobile data traffic
Ericsson: Mobile data traffix to increase 10X by 2016
Cisco: Mobile video will be 66% of data traffic by 2015
Survey: 83% expect carriers to provide Wi-Fi service as part of bundle