The charger/headset jack for the F3 Motofone (and variants) was not a standard 2.5 mm or 3.5 mm headset port. It was a DC connector that can support mono sound quality. This is not well documented at Motorola, and internal documentation indicates the jack is a standard 2.5 mm TRS connector jack. The jack shown on the Motorola site clearly has a pin in the center of the jack, prohibiting use of a standard 2.5 mm plug. A mono headset was available as part number CFLN6103AA and the name of it is Motorola S215 Pedestrian Kit. This is a headset only and not an adapter.