Anyone who has RingCentral login credentials will be able to join E2EE meetings. However, only users who belong to paid accounts can initiate E2EE meetings. This includes both free and paid users in those accounts. Scheduling and starting ad-hoc E2EE meetings are not available for free accounts.
Note: Users will not be able to join by telephone, SIP/H.323 devices, as these do not support RingCentral SDK to perform end-to-end encryption.