The user doesn't exist in the tenantIssue While adding an external Call Participant using email under table notify_conference_call error/notification "The user doesn't exist in the tenant" could be observed. The issue that the user is experiencing is normal. With a multi-tenancy architecture, different tenants can use the same physical instance of the app. Each tenant receives a separate logical instance of the app, even while tenants share physical resources (such VMs or storage). What is multitenancy? A tenant is a group of users. In a SaaS application, the tenant is a subscriber or customer of the application. Multi-tenancy is an architecture where multiple tenants share the same physical instance of the app. Although tenants share physical resources (such as VMs or storage), each tenant gets its own logical instance of the app. Typically, application data is shared among the users within a tenant, but not with other tenants. Reference: Multi-tenant architectureCauseThe below script include is giving error message "The user doesn't exist in the tenant" as an external user/email ID is being added Script Include - NotifyJSTeamsConferenceSNCAPI: /sys_script_include.do?sys_id=69354db60ff61010ab3779aca8767e9fisValidHost: function() { var hostEmail = this.getHostEmail(); if (hostEmail === "") { this._addErrorMessage(gs.getMessage("Meeting host must have a valid Teams Email Address")); return false; } else if (!this.updateTeamsUserInfoFromEmail_throws(hostEmail, gs.getUserID(), true)) { var errorMessageIndex = this._result.errorMessages.indexOf("The user doesn't exist in the tenant"); if (errorMessageIndex != -1) this._result.errorMessages.splice(errorMessageIndex, 1, gs.getMessage('Meeting host must have a valid Teams Email Address')); return false; } return true;ResolutionAlthough we can add users from other tenants as guests, we are unable to add users from other tenants directly.The user must achieve this by creating a user in the tenant directory with the role of guest.To learn more about this method, refer to Add a guest user and send an invitation