Just ensure that your voicemail set up within 60 days, or else, it will be removed from your account. Just click the "Phone" App from the home screen of iPhone. You can press "1" or the "Voicemail" key to access to voicemail on AT&T phone.
Open your phone’s voicemail app, then tap (or in some cases, tap and hold) the message you want to save. You should be presented with a list of options; the save option will usually be listed as “save”, “save to phone,” “archive,” or something similar.

When you first set up your Android phone, it may ask you to record your greeting for the caller. You can also keep the default greeting stored on the device. But, in future, if you want to customize the Voicemail greeting or want to create a new one, then you may need to delete the old recordings from Android. It may not be necessary depending on the Android device model & version; it’s good to know the process.
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.