Increasing Number of Attendees

Hello,

As you mentioned you can buy a Large Meeting Add on to increase the participant number of a meeting.

Large Meeting is an optional add-on for Meetings plans that allows you to host up to 500 or 1000 participants depending on the license purchased. In large meetings, everyone can participate with audio, video, and screen sharing at their and the host's discretion. Learn more about purchasing and assigning large meeting licenses.

More details are available In this Zoom support article;

https://support.zoom.us/hc/en-us/articles/201362823-Enabling-the-Large-Meeting-add-on 

Regards

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