Nokia Siemens Networks announced some major leadership changes. Sue Spradley, who joined Nokia Siemens Networks in July 2007, is stepping down to pursue opportunities outside the firm.

Spradley will continue to serve as a non-executive advisor to Nokia Siemens Networks and as a member of the company's external advisory board. She will be succeeded by Rick Corker, who is currently head of the company's Asia-Pacific region. Corker will be based in Dallas and his appointment is effective from April 15. 

Bosco Novak, executive board member and head of customer operations west for Nokia Siemens Networks, wished Spradley the best in the next step of her career. "Sue has been a key member of our team during an important time in our history, expanding our customer base and strengthening our position with existing customers," Novak said in a statement.

Paul Tyler will succeed Corker. Tyler is currently head of sales for the company's Network Systems division in the Asia-Pacific region.