Skype, the eBay ( EBAY) subsidiary, plans to release a version of its Internet-based phone software for Apple's ( AAPL) iPhone, according to published reports.

The move, set to be announced Tuesday, puts Skype more directly in competition for wireless voice services with companies such as AT&T ( T) and Verizon Wireless, a unit of Verizon Communications ( VZ) and Vodafone ( VOD), the Wall Street Journal reports.

Skype's software, which can be downloaded free, allows iPhone users to call other Skype users on computers or supported cellphones free if they are in a Wi-Fi hot spot, the newspaper reports. Or they may call landlines for a fee, of typically 2.1 cents a minute.

Skype's chief operating officer, Scott Durchslag, said the iPhone product is part Skype's strategic push toward cellphones, as opposed to the calls from computers, for which Skype is known, the Journal adds.

The news of the iPhone software from Skype was previously speculated in the blog GigaOm.

BusinessWeek reports the deal would put Skype's service in the hands of millions of potential new customers and give its 400 million current users new ways of logging more airtime. Skype will be available for free downloading from Apple's iTunes App Store on Tuesday.

Wireless versions of Skype are only one facet of Skype President Josh Silverman's plan to spur growth, according to BusinessWeek. The company plans eventually to launch its service everywhere users may log on to the Internet, including phones, televisions, cars, and their work PCs, Durchslag told the magazine.

Just last week, Skype announced a service that allows businesses to make cheap Internet calls over existing office-phone systems.