Mobile end-user average revenue per user dropped between 6 to 9 percent globally, year-over-year in 3Q-2009, compared to 3Q-2008. Mobile Internet services, however, should make up this drop in call revenue.

In Europe the ARPU contraction was in the range of -5 to -8 percent, with Austria seeing a contraction of more than 9 percent.

India, the world's second-largest market in terms of subscribers, saw average revenue per user (ARPU) dropping more than 10 percent YoY in the same period, as new operators and the introduction of per-second billing put heavy downward pressure on voice revenues.

However, ABI Research estimates that ARPU decline is likely to flatten out in developed markets in Europe and North America as mobile data revenue increasingly replaces falling voice revenue.

Globally, the growth in Minutes of Use has also peaked, and is expected to grow at a CAGR of only 1.4 percent between 2009 and 2015. Much of this growth is driven by developing markets in Africa, Asia, and the Middle East.

"With the decline in voice revenues, mobile operators must aim to increase the uptake of mobile Internet services and revenues to defend their ARPU," says analyst Bhavya Khanna.

"Mobile data traffic has exploded in the past two years, and is expected to expand at a compound annual growth rate (CAGR) of over 40 percent from 2009-2015.

"Operators can cash in on this demand by enlarging their mobile broadband coverage, thus increasing their user-base. This has started to happen in developed markets such as the UK and US, where mobile Internet service revenues have grown over 12 percent and 8 percent YoY respectively."

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