RONA must expire before voicemail answers. Cisco's voice channel guidance for Webex Contact Center and Webex Calling explains that, when agents use Webex Calling endpoints, unanswered contact center calls should be redirected back to the contact center queue before the endpoint's voicemail rule answers. If voicemail answers first, the customer call is effectively consumed by the agent's mailbox instead of being requeued for the next available agent. Setting the RONA timer shorter than the voicemail ring interval causes the contact center platform to classify the offered contact as no-answer and requeue it. Direct calls to the agent still follow the normal Webex Calling voicemail configuration, so voicemail continues to work for non-contact-center calls. Making RONA longer than voicemail is exactly the wrong direction. Two lines may help operational separation but are not required for this behavior. Disabling voicemail would break the stated requirement that direct unanswered calls roll to voicemail. Reference: Cisco Help, Set up voice channels for Webex Contact Center.