When a call comes in, Talkdesk tries to ring all available agents. If there are no agents available because they are busy taking other calls, Talkdesk sends the call to the waiting queue. If a call is not answered within the "Waiting Time Limit" it will be sent to voicemail. Calls are also sent to voicemail if all agents are offline. The If-No-Answer phone number is a backup number to which the call is sent before going to voicemail.