Specifications: This amazing adaptor converts the standard 3.5mm smartphone plug to an for Aastra RJ9, RJ10, or RJ22 handset plug, allowing you to use your favorite smartphone headset with your for Aastra office phone. The adapter outputs binaural sound for stereo headsets, meaning you will hear sound out of both ears. Convert 3.5mm OMTP smartphone plug to single 4P4C RJ9/RJ10 handset/headset plug. Save money by buying a smartphone headset, or using your existing one with your office phone's headset jack. This adapter will not work with for Apple EarPods and other CTIA based headsets. Works best when paired with an amplifier. For optimal use, please plug into the headset jack on your phone. The handset jack usually causes audio distortion. Compatibility: This list is not all inclusive. Updated 3/1/17. Incompatible Phones: For Avaya 1100, 1200, 1600, 2000, 4600 and 9600 Series For Cisco 7902, 7905, 7910, 7911, 7912, 7920, 7921 For Nortel 1140T and Visa 350 For Polycom Phones For Shortel IP 230 For Uniden Dect2088, TRU9496 For Western Electric 6250 Incompatible Headphones: For Apple EarPods. Compatible Phones: For Aastra/Packet8/8x8 480e, 480i, 53i, 55i, 57i, 57iCT, 6753i, 6755i, 6757i, 9112i, 9133i, 9143i, 9480i For Allworks 9212 For AltiGen IP Phone 500, 510, 600, 705, 710, 720 For Avaya 4500 Series IP For ESI 48-Key IP Feature Phone and 48-Key Digital Feature Phone For GE Model 2-9451 For Inter-Tel For Lucent 8410D For Mitel IP 40XX, 41XX, 5000, 50XX, 5140, 52XX, 53XX, 5550 For NEC Dterm Series E For Norstar T7316E, M3904 For Nortel IP 1120E IP, 1140E IP, 1150E IP, 1230, i2002 and i2004 For Nortel Meridian Norstar Northern Telecom For Panasonic Hybrid For Plantronics T10 For Possum Sero For Shoretel ShorePhone IP Models For Siemens For Splicecom PCS 520 For Talkswitch IP Phone, TS-600 For Toshiba For 3COM 3102, 3103 Compatible Amplifiers: For Plantronics S-12, M22, A20, MX10, TSB, AP15 Item Name: 3.5mm to RJ9 Cable Length: 20cm/7.87inch; (Approx.) Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 1 x 3.5mm to RJ9 Cable