Permira will take a 25% stake in the publicly-listed Freenet, which now becomes the third largest provider of mobile phone services in Germany with around 19 million subscribers, behind T-Mobile and Vodafone.
Debitel was sold by Swisscom in June 2004 and delisted from the Frankfurt Stock Exchange in May 2005. Permira paid €842m for the business.
Both Freenet and Permira are subject to a lock-up period for 60% of the new shares until next year.
Freenet shareholder United Internet opposed the deal. Already an owner of 25% of Freenet, it proposed an offer of €16 per share on condition it did not acquire Debitel. According to a Thomson Reuters report, United Internet wanted to split up Freenet, keeping the internet business and leaving the mobile telecoms part for fellow shareholder Drillisch.