Nokia’s chief executive says the mobile phone market’s main players include are Google, Microsoft, Apple and Samsung Electronics.

You can compete with some of them some of the time, but not all of the time. So you must partner,” Nokia’s Olli-Pekka Kallasvuo said during an interview at the All Things Digital conference this week.

Nokia is currently giving away the Symbian operating system, which Kallasvuo calls the only mobile OS today that is both open and mature. He said this was an advantage when competing with Apple and Google. However he acknowledged Nokia has two other systems which it is not giving away in order to address different sectors of the market.