Premium quality Y splitter adapter cable allow users to split out the connectors to be able to use up to two headsets connected into one cable into the telephone for training purposes. Compatible phone models : Compatible telephone and Models : ( Not for Avaya model 9608 9608G 9620L 1608-I ) AVAYA / Lucent: 6402D, 6408D+, 6416D+M, 6424D+M, 8403, 8410D, 8434DX, 4406D+, 4412D+, 4424D+, 4424LD+, 1120, 1140, 1165, 1210, 1220, 1230, 1408, 1416, 3904, 3905, 7208, 7316, 9404, 9406, 9408, 9504, 9508, 2410, 2420, 5410, 5420, 5610, 5620, 5621, 5625, DT1, DT3, DT5, QE4610, 4610, 4610SW, 4612, 4620, 4621/SW 4622/SW, 4625/W, 4630/SW. Not for Avaya model 9608 9608G 9620L 1608-I. Aastra: 2465, 2564, 390, 480, 480e, 480i, 51i, 53i, 55i, 57i, 57iCT, 554, 564, 565, i733, 1120e, 1140e, 1150e, 1210, 1220, 1230, i2002, i2004, i2004, IP i2004 ,Phase II i2052, 7406, 8540, 9617, 6730i, 6731i, 6739i, 6751i, 6753i, 6755i, 6757i, 6757i, CT 7446i, 9112i, 9133i, 9116, 9143i, 9480i,Dialog 4222, 4223, 4224, 4225, M2216 (ACD I or II), M3905, M4000, M4020, M7208, M7308, M7310, M7316, M7324, M4000, M4020, M5208, M5209, M5216, M5317, M7900, M8001 ,M8003, M9009, M9516, Powertouch 480, 480e, 480i, i2002, i2004, i2004 IP (not for i2400 phase II and i2004 POE ). Northern Telecom (Nortel Norstar): 1120E IP, 1140E IP, 1150E IP, i2002 (ip2002), i2004 (ip2004 (not for i2400 phase II and i2004 POE ), 1210, 1220, 1230, 2465, 2564, NTZK23AA, AB: (M2216):ACDI, Vista Powertouch 480, 480e, 480i, M2008, M2216, M2616, M3903, M3904, M3905, M7208, T7208, M7308, M7310, M7316, T7316, T7316E, M7324, M7900, M8001, M8003, M9516, M9009, NT8B20, NT8B30, NT8B40, NT8B50, Meridian Option M3110, 3310, 3820, Plantronics: A100, S10, S11, S12, S50, T10, T20, T50, T100, T110, SP-02, SP-04, SP-05, A100, T50, T100, PLX-400, PLX-500.