Updated: Up to 10,000 Skype customers have to change their SkypeIn number by 20 December, an email to customers advised last night.
By way of recompense, it also offered affected punters a year's free service with voicemail and a grovelling apology.
According to the email, Skype is having to "return some of the 0207 SkypeIn numbers" to their suppliers, though it makes no mention of why, or to whom, these numbers need to be returned.
It seems numbers starting "020 7870" are affected, which Ofcom shows are allocated to a company called Gamma Telecom. Skype leased these numbers from an intermediary called GCI Telecom, who tell us that they are still in negotiations with Skype regarding the numbers, and have promised us a fuller explanation real soon now.
Skype's message board is full of complaints from users about to lose their numbers, who have printed up business cards or even "...had to pulp a mailshot to 3,000 people, already stuffed, stamped, and ready to go, with first class stamps stuck on".
This adds to the firm's list of recent woes.
The failure of Skype to explain what went wrong, or provide any evidence that this won't happen again, hardly fills one with confidence - and while tin cans and string might not provide the same quality of connection as Skype's VoIP technology, it seems that system might be just as reliable. ®
GCI Telecom tells us that "negotiations broke down" between themselves and Skype, but anyone wanting to keep their number should mail them directly as they'll be happy to provide a VoIP, or forwarding, service.