"Nokia and Siemens today announced the appointment of Jesper Ovesen as Executive Chairman of the Board of Nokia Siemens Networks, effective today (Thursday)," the companies said in a joint statement.

Kallasvuo was ousted as Nokia chief executive in September 2010 after running the company since 2006, blamed for a decline in innovation and competitiveness that left the former undisputed giant vulnerable to its market rivals.

When Stephen Elop took over Nokia, Kallasvuo stepped down from Nokia's board but retained the non-executive chairmanship of Nokia Siemens Networks (NSN), a telecoms equipment joint venture.

According to NSN, Kallasvuo chose to leave the board because he could not do the job full-time.

"We would both like to extend our sincere thanks to Olli-Pekka for his contribution and dedication to Nokia Siemens Networks," said Elop and Siemens chief financial officer Joe Kaeser in the statement.