... . and Desk Telephones with RJ9 / RJ22 Headset Socket CallTel Headset Model Number T200 CallTel T200 Polaris Monaural Headset is also known as ... , 510, 600, 705, 710, 720 Ascom: Berkshire 200, 400, 600, 800, SD30, MR30, MR51, MR61 AVAYA / Lucent: 6402D, 6408D+, 6416D+M ... and 48-Key Digital Feature Phones General Electric: GE Telephone Model 2-9451, 2-9490 GrandStream IP Phones: Budgetone 101, Budgetone ...