Yes. If you're in a conference room and it's not a Zoom Room(tm), or has a Cisco system, or whatever, you have to use the conference phone. You might be able to tell the Zoom meeting host to call the conference phone and bring it into the meeting, but it'd be easier just to type the ID in (unless it was really 128 char, but then that'd give people a reason to buy new conference hardware I guess).

Also if you don't want to install the Zoom client, you can just dial in from your cell phone or desk phone.