You find “Dial-in numbers” (if available) under “Account settings” in the left hand side navigation. Your platform administrator decides whether your own dial-in numbers are available. See Features.
If available, you can use your own telephony system with your own phone numbers and internal dial codes to dial into a meeting. Follow the instructions on the “Dial-in numbers” page to configure your telephony system before you proceed.
Under “Custom dial-in numbers” the page lists the SIP identities of your platform: “Configure your PBX and forward the calls to the following SIP identities:”. There is one SIP identity for each language of the voice prompts (“IVR language”). Forward the calls to the SIP identity in the language your callers should hear.

Add the dial-in numbers that you have configured in your telephony system.
These dial-in numbers will appear in the meeting invitation emails and the meeting room.
Your numbers are listed under “Your dial-in numbers”. To delete numbers, select the check box(es) in front of them and click on the red “Delete selected dial-in numbers” button.

Once you have added your own numbers, you can decide whether the standard numbers of your platform also appear in the invitation. Check “Display standard numbers in the meeting invitation” to show them. While it is checked, the standard numbers are listed below it.