It’s official. Skype for iPhone will finally be available to download from the iTunes App Store on Tuesday and its version for BlackBerry will be launched in May, according to Reuters.

The move puts Skype more directly in competition for wireless voice services with AT&T and Verizon Wireless.

The internet phone company now has more than 400 million users worldwide, and the number continues to rise as they expand further onto mobile phones.

“The No. 1 request we get from customers is to make Skype available on iPhone. There’s a pent-up demand,” company COO Scott Durchslag said in an interview.

Skype for iPhone will allow customers to use their existing iPhone address book, so users do not need to duplicate lists. It will also allow patrons to take a picture of themselves to use as their avatar.

This year, the company announced versions of its software for Nokia and phones running Microsoft’s Windows Mobile and Google’s Android operating systems.