Hello,
If your meeting includes phone and/or room systems participants, the invite will include a numeric number for alphanumeric passcodes for them to dial in with. This can be found in the dial in settings for the meeting invite:
-Have the host of the meeting go to Zoom.us and click on the title of the meeting.
-Click on the Copy Invitation next to the meeting invite link:

You will see dial in options there to join via H.323 and there will be a numeric passcode there.
It will say "
Join by SIP
...(details for joining)
Join by H.323
...(details for joining)
Passscode: (numeric)
Let me know if this answers your question by marking this answer as a solution!
Thanks,
Micah