«The phone rang in Clark Taylor's house at nearly three in the morning. He answered it only after the FIFTH ring. Although nearly ten years had passed since THEIR last meeting, Clark was able to recognize the voice. It belonged to Martin Hall, one of the BRIGHTEST math students he had ever had.
In many cases, an update to your carrier’s voicemail app or settings can resolve the issue, but don’t forget to call your voicemail number to check if it is set up correctly. Once you’ve set up your voicemail, you’re free to switch off when you need to. There are other ways you can stay in contact, however.

You can record custom messages right from your dashboard using Dial-and-Record, which allows you to record it through your phone. Then, once they’ve been recorded, they’re saved in your account to be placed in any section, such as for the welcome greeting, menu prompt, or voicemail greeting, in addition to other sections. Enter the number of rings between 0 and 9, or press #. If you choose 0, calls will go straight to your voicemail without ringing first. If you choose # calls won't go to voicemail at all. The phone will ring until you answer or the caller hangs up. Follow the voice prompts.
So if you don’t have access to Visual Voicemail, you can still likely use the traditional kind of voicemail.