Hi @jgam thank you for your post here on the Zoom Community! If you want to allow people to connect into your meetings by telephone (as well as computer Audio over the internet) you can select that option in your settings in the Zoom web portal.
If you sign into the Zoom web portal and go to Settings
Under the "Schedule Meeting" section you should see an option for Audio Type
There is also an "Audio Conferencing" tab at the top with some more options.