A dentist is similar to a doctor. Unlike a doctor, a dentist is going to get far more non-urgent calls as patients will want to know when they can pick up various orders, as well as to book follow-up appointments. The key here is prioritizing so the dentist can respond promptly to the patients who need emergency dental work and other urgent consultations.
Most of the time, voicemail isn't working on your iPhone 8 Plus because of a software issue. Voicemail on your iPhone is known as Visual Voicemail, which downloads audio files from your wireless carrier onto your iPhone.

With this method, you don’t need a third-party app. Call the person you want to chat with, then tap the “Add Call” button on your phone’s screen. Dial your own phone number—the one you’re calling from. This will take you to your voicemail. Once your voicemail has started recording, tap the “Merge Calls” button on your screen. Now, you’ll record your phone conversation onto a voicemail message. When you’re done with the call, you can tap the share button to export it to your Mac via Airdrop, to the Voice Memos app, or transfer it via email or text message. The file is recorded as an M4A, so depending on what you want to do with it, you may need to convert it to MP3 before uploading it to other apps.
Most of the time, an update to your carrier’s voicemail app or settings will cure the issue; however, it is important to confirm that your voicemail number is appropriately configured before proceeding any further.