Sennheiser - EPOS CCEL 191-2 (CCEL191-2)

DECT / GSM cable. EasyDisconnect with 100 cm cable to 2.5mm 3-pole jack. For using a SC 230, SC 260, SC 630, SC 660, CC Series or SH Series headset with a DECT / GSM phone with 2.5mm 3-pole jack.

To help you find connector that works with your device, please visit Sennheiser Headset Compatibility: https://www.eposaudio.com/en/ch/enterprise/headsets/compatibility-guide