Hi @james.snider ,
Just to check, the users that you cannot hear....is their Webex Meetings client bringing them in as mute upon join (so would need to press the unmute on the screen to speak).
You have the option to set this from the Meeting preview window before joining.
![2020-06-08_15-51-28.png 2020-06-08_15-51-28.png](https://community.cisco.com/t5/image/serverpage/image-id/76261iE5DB42735EDADFB4/image-size/small?v=v2&px=200)
Are you also seeing a phone icon by their name in the participants list?
![2020-06-08_15-54-53.png 2020-06-08_15-54-53.png](https://community.cisco.com/t5/image/serverpage/image-id/76263iF88DA090CA8BFD89/image-size/small?v=v2&px=200)
Many thanks