Just came upon this page – followed each successive step – the RESET NETWORK SETTINGS solved my issue, perfectly. Thank you so much for this tutorial – saved me a ton of aggravation, money and time.
3. Setting Up an AT&T Visual Voicemail: Open your iPhone's Phone app. It's the white phone icon on a green background on the Home screen. Tap "Voicemail". It's in the bottom right corner of the screen.

Here, the pet care company leaves multiple options to fulfill the needs of the callers. They also have the option for attending to callers with immediate needs.
How do I change my voicemail greeting on Android? Open the Phone app . Press and hold “1” to call your voicemail. Enter your PIN and press “#”. Press “*” for the menu. Press “4” to change settings. Press “1” to change your greeting. Follow the recorded instructions. Access your main voicemail menu. Listen for instructions to enter your password. From the main menu press 3 for Personal Options. Press 2 for Greetings. Press 1 to Change Greeting. Press 1 to Record personal greeting or press 2 to select the standard greeting. Tap on Call settings and select Voicemail. Tap on Voicemail service and select My carrier or My operator. Tap on Setup, select Voicemail number and type in your voicemail number. Tap on OK in the Voicemail number changed popup.