Problems installing Ring Intercom with BITRON AN XXXXXXXXXX

Hi All, I've recently bought a Ring Intercom and I'm trying to install it with my bitron an XXXXXXXXXX. Based on the description on ring cable : https://ring.com/gb/en/support/articles/4f7mk/wiring-differences-2022-2024-intercom I'm assung that i have a 2024 cable. Based on the Bitron switch description C7 Call (electronic) 11 Call (AC buzzer) 1 Speech In (Speaker) 2 Speech Out (Mic) 9 Lock 6 Common I've performed the following connections: Ring cable C2 --------------> 1 C3 --------------> 2 C4 --------------> 6 C5 --------------> 9 C6 ----> Don't know were to connect I assume beased on the descriptions on both Ring documentation and Bitron that his should be the setup. Still I don't know where to connect C6. Can you help ? Can you please confirm tha ths is the setup I neeed ? regards Luis Meira