Convenient headset and recording capability.  Ideal for call centers, brokerage firms and insurance agencies which require carbon power amplifiers and/or recording capabilities. Two jacks support amplified Siemens headsets or supervisor monitoring; another supports 600 ohm recording devices for desktop recording applications. As required by law in some states, the Headset Plus Adapter can emit a recording indication beep tone. Snaps into the module bay under the Optiset E Advance and Advance Plus phones. Works with Siemens M-10 or M-12 Modular Amplifier.