Engineers at Skype, the internet-based telephone and message service, appeared to have solved a software problem on Friday that had shut down the system for more than 24 hours and left many of its 220m customers without service.

The Luxembourg-based company, owned by eBay, the online auction company, attempted to reassure its customers and blamed the problem, which prevented many users signing on to the service, on a software glitch rather than a cyber attack.