By Dan Levine SAN FRANCISCO (Reuters) - Nokia may have sold its handset business to Microsoft but by hanging on to its valuable patent portfolio, the Finnish company can try to boost royalties by sueing Android phone makers, or unload the patents in a future deal. Nokia, once the world's dominant handset maker, has failed to close a yawning lead opened up by Apple and Samsung in the highly competitive market for smartphones. It will now concentrate on its networking equipment unit, navigation business and technology patents. Microsoft on Tuesday agreed to pay 3. ...



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