Motorola

Whenever you are using the phone (for a call, either answering one or generating one), look at the "right smart key". It should state "Speaker". By pressing this key, the phone will toggle to speakerphone. You can even close the flip and the call will still be on. But beware! Whenever finishing the call, you have to press the smart key again to toggle off the "speakerphone". If you don´t do that, the call will be on and on and on...

Hope it helps.
Rubens ;)