You can configure your meetings to only use PSTN/Telephony (telephone dialing) audio. In Zoom Rooms, you will need to have a PSTN Phone, VoIP Phone or SIP Dialer (e.g. Revolabs UC1500/1000) in the room.
1. Schedule a meeting on the Web portal, Zoom Client, Outlook Plugin or Google Extension. Click on Telephony Only. (Note: it will remember this setting for any new meetings being scheduled)
2. Start the meeting on the Zoom Rooms iPad controller. Click on the i icon and it will display the dial-in PSTN/Telephony information.
3. On your PSTN phone, VoIP phone or SIP dialer, dial the number, then enter meeting ID and participant ID.
Note: You must enter the correct participant ID to bind with the Zoom Rooms audio, otherwise you may encounter echo. If you hear echo, hang up the phone and dial again.