To enable or disable your voicemail password :
Step 1. Dial 123 from your mobile phone.
Step 2. Select option 4 from the voicemail main menu.
Step 3. Select the desired option: "enabl" to add a password or "disable" to remove the password.
For your enabled password, more than five failed attempts will result in your voicemail box being restricted. You will be required to contact Customer Care from your mobile to have your password reset.
For security purposes, you will still be required to enter your password when you are roaming, or accessing your mailbox from another phone.