Hookswitch Adapter- Polycom The APP-50 transforms your Polycom Unified IP phone experience through remote answer/end and ring alert. It is compatible with the following Polycom Unified IP Phone models: 320, 330, 430, 550, 560, 650, 670. Supported Polycom phones include the SoundPoint IP 320, IP 330, IP 430, IP 550,IP 560, IP 650 and IP 670.