When the user control is applied, Unified CM expects to receive an explicit notification in the form of a DTMF digit, even after the voice channel connects a call.
Depending on the VoiceMail Selection User Control Delayed Announcement Timer, Unified CM may not insert any announcement. When you apply user control, Unified CM ensures that the PSTN side answers the call before extending the call.
If the client is not registered, the announcement always plays for RD or MI.
In case of a failure scenario, Unified CM tries to send an error message that indicates the call failure via data channel. For SendCallToMobile, Unified CM displays the following error message on the desk phone with SendCallToMobile enabled:
Call fail due to Voicemail selection failure, please retry or contact system administrator.
Cisco Unified Communications Manager Administration considerations
The following service parameters in Unified CM allow you to define the behavior of SNR voice mail.
Voice Mail Selection Policy
The Voice Mail Selection Policy drop-down allows you to select either Timer Control or User Control. The default is set to Timer Control.
Voice Mail Selection User Control Delayed Announcement Timer
Unified CM uses this timer to delay the announcement that is played to RD users after they answer an RD call.
If Unified CM receives a user answer notification in DTMF or a data channel that the smart phone client generated, Unified CM does not play the announcement and connects the calling and called parties.
If Unified CM does not receive a user answer notification within the allotted time, Unified CM plays an announcement that prompts users to enter a DTMF digit to have their call connected.
If the client is able to send the DTMF digits or a notification via the data channel, the client ensures that the system sends the explicit answer notification after a user answers the call.
The default is set to 1 second.
Voice Mail Selection User Control Confirmed Answer Indication Timer
Cisco Unified Mobility uses this timer to wait for an answer notification, either from the received DTMF or from the mobile client via a data channel. When the timer expires, Cisco Unified Mobility drops the call.
The default is set to 5 seconds.
The Unified CM service parameter at the system level controls Single Number Reach Voice mail. The RD/MI device level setting controls the feature as well, however, the device level setting overrides the system setting. Unified CM uses the system setting if the device level setting is set to Default.