Cause 1 of 4: The voicemail number isn't saved in your phone
To listen to your voice messages, you need to save the voicemail number in your phone.
Solution: Save the voicemail number.OR Call 171 to check your voice messages.
Enter the voicemail number
Key in *5005*86*(prefix) 5 (your phone number)# and press Call.A request to change the setting is sent to the network.