Amazon.com: WirelessFinest Headset Headphones with Volume + Mute Control Replacement for Cisco SPA Series Spa303 Spa504g and Other, Polycom Soundpoint IP 320 330, Grandstream, Cortelco : Electronics
Plantronics HW540 Headset Package for Cisco SPA300 and SPA500 Series IP Phones
Cisco SPA303 3-Line VoIP Phone - spa303
Amazon.com: TruVoice HD-500 Premium Single Ear Headset with Noise Canceling Microphone and 2.5mm Cable for Cisco SPA303, SPA502g, SPA504g, SPA508g, SPA509g, SPA514g, SPA525g and Phones with a 2.5mm Headset Port : Electronics
Amazon.com: WirelessFinest Headset Headphones with Volume + Mute Control Replacement for Cisco SPA Series Spa303 Spa504g and Other, Polycom Soundpoint IP 320 330, Grandstream, Cortelco : Electronics