If you want to re-enable the Voicemail service on your Android device, then you can easily do that from your phone settings. I hope this guide will help you in deleting your old Voicemail greetings and record the new ones for the callers.
When you reset network settings, all of your iPhone’s Wi-Fi and cellular network settings will be erased. This includes your Virtual Private Network (VPN) settings, your Bluetooth devices, and your Wi-Fi networks — so make sure you write down your passwords first! We do this step because it can be very difficult to track down the exact source of a software problem, so we reset all network settings.

That way you'll get to know exactly what other people hear when they call your phone and one last thing I wanted to show you. If you don't see that play on record option on the bottom, you don't have visual voicemail. Set up on your phone and that's through your provider. So if you have at and T sprint T-Mobile or any other provider, you need to have visual voicemail.
At this point, do not insert a new SIM card, or you might lose the voicemails that you saved on your iPhone. (Click to see How to undelete Voicemail from iPhone) 2. Use Automated System to Reset Password (Call 611) Call 611 and enter the wireless number starting with area code. Press 3 to “get help with voicemail.” Press 3 to reset your VM password. Enter the Billing Zip code for your account. In a few seconds, iPhone will prompt you the message "Password Incorrect - Enter Voicemail Password." Enter the last seven digits of the wireless phone number and tap OK.