Facing mounting privacy concerns, Apple has begun to reject mobile applications that require access to an iOS device’s unique device identifier number (UDID), according to a report from the Web site Techcrunch. 

The company announced last summer it would be phasing out UDID numbers with the launch of iOS 5 but the report from TechCrunch on Saturday quotes several application developers confirming that the company was outright rejecting developers whose applications requested the numbers.

UDIDs are strings of 40 characters that essentially serve as a serial number that can be used to track devices like iPhones or iPads. The numbers have proven useful to advertising companies, analytics firms and application testing systems.

Two of Apple’s 10 review teams started doing “blanket rejections” last week. Two more teams will start processing rejections this week, according to the report. Eventually all of the teams will be able to review and reject applications using UDIDs.

Going forward, mobile application developers who previously used UDID information will be forced to look into alternate methods of tracking their users. Andy Yang, chief executive at Playhaven, a company that monetizes games for developers, was certain a sea change was coming.

“In the next month or two, this is going to have an impact on all ad networks and apps using advertising. Everybody’s trying to make their own choices about what to use instead,” he told TechCrunch Saturday.

Mobile phone manufacturers like Apple have faced criticism over what have been deemed privacy-invading features and practices.

Just last week two ranking members of the Committee on Energy and Commerce sent privacy inquiries to companies behind 34 different applications available in Apple’s App Store. Companies like Tweetbot, Pinterest, Soundcloud, Twitter and Facebook were mailed letters on March 22 and asked to describe exactly what type of information they gather from users.

Photo-sharing social network Path caught heat earlier this year after it was found uploading users’ contacts to their servers without users’ consent. While Path soon remedied this, it eventually led to the discovery that developers could harvest users’ photos via iPhones through certain applications’ location data.

Categories: Apple, Compliance