HPPFOTRS Call Center Headset Splitter Training Box Adapter for Nortel Meridican, Norstar, Avaya, Ashtra, Mitel, Polycom, Ge and Other Ip Phone Allows the use of two handsets on one telephone.Ideal for telephone marketing training purposes.The plug on the cable is 4P4C, some call it RJ9.Also Known as a Handset Splitter The training connection is not muted. Both the trainer and the trainee can be heard on the call. Without adapter line(NO.1/NO.2/NO.3 Line) can be used , including call centers dialpad, as well as most of the Analog desktop telephone (Philips, Siemens, CHIND-E, BOTEL etc. Most of Analog desktop telephone) We offer three adapter (NO.1 line,NO.2 line, NO.3 line). NO.1 Line: Cisco, digital / IP telephone NO.2 Line: AVAYA, Panasonic digital / IP telephone NO.3 Line: other parts Analog desktop telephone.