Skype, the free web based software based telephone service, said it's returning to normal after its experienced downtime earlier today.

In a tweet, the Luxembourg-based company said, Skype is now gradually returning to normal - we expect it may take several hours for everyone to be able to sign in again, however.

Skype explained the issue in a blog post by company spokesperson Peter Parkes. According to Parkes, the problem came about because many of the supernodes, individual connections between computers and phones that help the company operate, were offline because of a problem affecting some versions of Skype.

Parkes said the company's engineers are in the middle of creating new 'mega-supernodes' as quickly as possible to return the service to normal. The last time Skype had an outage of this magnitude was back in 2007.

Early afternoon, or mid-morning for those in the Pacific Time zone, many Skype users started to complain via Twitter that their service wasn't working. Shortly thereafter, the company, which has its network operated by a Luxembourg-based company called Skype Limited, addressed its users in a tweet.

Some of you may have problems signing in to Skype - we're investigating, and we're sorry for the disruption to your conversations, the company tweeted, while adding later, Our engineers and site operations team are working non-stop to get things back to normal - thanks for your continued patience.