This is the normal behavior which is the feature of TTS (text to speech).
If Cisco Unity Connection finds that there is a Recorded Name for a CUC user, that is used.
If there is no Recorded Name for a CUC user and if the Display Name is not empty, the Display Name is run through the TTS engine. If you do not want the Display Name to be played back, you need to delete the Display Name of the user.Note: There is also an Enhancement included in CUC 8.0, where you have an option Use Text To Speech to Read Display Names When No Recording Is Available under Advanced Settings > Conversation. You can uncheck this check box to if you want CUC to play the extension number instead of the Display name. This is checked by default with which Cisco Unity Connection uses Text to Speech to play user display names for users who do not have recorded names.
If CUC finds that there is no Recorded Name, No Display Name, it will switch to the Extension Mode where it will read the Extension number.