APS-11 Electronic Hookswitch

The Poly APS-11 Electronic Hookswitch (HP MPN 85Q78AA, also numbered 37818-11) connects a Plantronics wireless headset system to a compatible desk phone. It is an electronic hookswitch cable/module for setups including Aastra and Siemens phones.

The EHS connection lets you answer a call remotely from the headset, replacing the mechanical HL10 handset lifter. A specialist listing also notes that the module can be used with an Online Indicator (OLI), making it useful in a headset setup that uses that indicator.