Despite its cosy advertisements asserting that Microsoft Corp is a customer rather than the competitor it is to IBM Corp, Deutsche Telekom AG is joining the biggest battle in Europe to trip Microsoft up, becoming an investor in the Bertelsmann AG-Axel Springer Verlag AG alliance with America Online Inc to see off the Microsoft Network. Telekom has an option to take a stake in America Online and in AOL, the European on-line venture being set up by Bertelsmann and America Online. Bertelsmann will give its own option for a further 5% stake in America Online to Telekom and the AOL joint venture will take a stake in T-Online, Telekom’s own on-line service. Springer is planning to take a stake in both T-Online and the local German activities of AOL.