Skype, one of the earliest providers of free VoIP calls and low-cost landline and mobile calls, announced that it has recorded 25 million users Skyping concurrently.

"Our software is designed to handle large numbers of concurrent users, with wideband audio and group video calls all flowing smoothly around the world," the company wrote in a blog post.

It has been a busy year for Skype. After filing for an IPO in August, Reuters reported the public listing would be delayed until next year when better market conditions could value the company at up to $1 billion.

This year, Skype forged partnerships with channels like Verizon, Facebook and Avaya, as well as embedded itself into select mobile phones. In October, Skype also released its first Android app and named top Cisco executive Tony Bates as CEO.

Skype claims to have 560 million registered users around the world. At the time of its August filing, Skype said that its total number of active users grew from 52 million in 2007 to 124 million. Paying Skype users still represent a fraction however, with only 8.1 million at the end of June, bringing in an average of $96 per user.

See PCMag's review of Skype 5.0 for Mac OS X (slideshow below) and Skype 2.0 for iOS.