RJ9 HEADSET COMPATIBILITY: ONLY COMPATIBLE with Yealink T19P T20P T21P T22P T23P T23G T26P T27G T28P T29G T30P T31G T32G T33G T38G T40G T41S T42G T42S T46G T46S T48G T48S T53W T54W T56A T57W T58A Avaya 1608 1616 9608G 9611G 9620 9630 9640 9641G 9650 J139 J169 J179 Grandsteam GXP 1400 1405 1610 1615 1620 1630 2000 2120 2124 2135 2170 280 285 GXV 3005 3006 3240 3275 Snom 300 320 360 710 821 870 Zultys ZIP 33G 36G 37G 43G 45G 47G 49G 33i 35i and more deskphones listed in description | CRYSTAL CLEAR CHAT: Wideband Sound RJ9 Telephone Headset with microphone compatible with Yealink Avaya landline phones enables excellent sound quality for natural listening experience, features Noise Cancelling Microphone to reduce background noise, Acoustic Shock Protection Circuit to protect your hearing | MOST COMFORTABLE HEADSET: Super lightweight wired Hands-free RJ9 office Phone Headset compatible with Grandstream Snom Desk Phones with adjustable headband to fit all head sizes, high quality and soft leatherette ear cushion enhance all-day wearing comfort. Professional Mic Mute/Volume Control built in | ULTRA DURABLE: Precision design, quality plastics, unibody headband construction, superior quality microphone makes this call center phone headset with RJ9 jack sturdier and more durable. Compete with heavy duty Telephone Headphone for Call Center, Hospital, Office, Home, Insurance, Business, School, Bank, Telephone Counselling Services | 2-YEAR WARRANTY & COMPATIBILITY NOTES: 45 DAYS MONEY BACK GUARANTEE & 2 YEARS WARRANTY. ONLY COMPATIBLE WITH SOME SPECIFIC PHONE MODELS LISTED IN DESCRIPTION (include but not limited). Doesn’t work for Cell Phones and Computers. For Other Phones, Pls contact us for Compatibility Guide or Advice