The European Commission has sent questions to operators in Europe to determine whether Apple's sales tactics for the iPhone in Europe are shutting out smartphone rivals.
EU officials are looking into Apple's tactics.
The move follows reports from March that the European Union was looking into the handset contracts that Apple strikes with operators, following complaints by the operators.
Now, both the Financial Times and Reuters say they have seen a nine-page questionnaire sent by the Commission to operators that seeks to determine whether Apple sets distribution terms that ensure rivals are unable to secure a better sales deals. Operators have been given until June 17 to respond.
According to the Financial Times, the inquiry was prompted by private complaints from operators and is at a preliminary stage. Bloomberg quoted Antoine Colombani, spokesman for Competition Commissioner Joaquin Almunia, as saying that the EU antitrust regulator "has received information from industry players concerning Apple's distribution practices for iPhones."
"We are currently examining the situation," Colombani told Bloomberg. "This does not prejudge the Commission's position on the issues raised."
If the Commission decides that Apple has been using anticompetitive sales tactics for the iPhone, and has also been imposing technical restrictions that, for example, prevent the use of the iPhone 5 on certain LTE networks in Europe, Brussels could launch a formal abuse probe.
However, the FT noted that the Commission also has to be certain that Apple has a dominant position in the EU market, given the popularity of new Galaxy-branded devices from Samsung Electronics, for example, this could be harder to prove.
Operators have been critical of Apple's tight control of marketing and release dates for new iPhones, and the lack of iPhone 5 support for all LTE spectrum bands in Europe has also been controversial.
The smartphone market has been getting more competitive with new and compelling devices from Samsung and HTC on the market, not to mention the launch of BlackBerry 10 and growing sales of Nokia Lumia smartphones.
In the UK market, for example, data published by Kantar Worldpanel ComTech in February showed that while iOS and Android continue to take the lion's share of smartphone sales at 30.6 per cent and 56.2 per cent respectively, Microsoft's Windows Phones are now selling in significant quantities thanks to sales of Nokia Lumia devices as well as others such as the HTC 8X.
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