(PRODUCT DISCONTINUED). I know, I know... seems fake. But it’s definitely a real thing we sell on Amazon. Promise. Here’s the compat info per amazon. It’s an adaptor that converts a 2.5mm headset to an RJ9! It is only recommended from amplifiers. Customers trying it through the headset jack are doing so at their own risk! Here is a quick compat guide from Amazon: Compatibility ** Functions best when paired with an amplifier. This list (updated 10/1/2016) is not all inclusive. Please look up the specifications on your specific phone to see if it has a RJ9, RJ10, or RJ22 headset jack. Please let us know if you find more compatible phones or incompatible phone models. Incompatible Phones: Avaya 2410, 1600 and 9600 series Cisco phones Nortel 1140T and Visa 350 Polycom phones Uniden Dect2088, TRU9496 Compatible Phones: Aastra/Packet8/8x8 AltiGen IP Phone 500, 510, 600, 705, 710, 720 Avaya 4600 Series IP ESI 48-Key IP Feature Phone and 48-Key Digital Feature Phone GE Model 2-9451 Inter-Tel…