If resetting your Networks Settings doesn't work, the Apple forums suggest enabling Airplane mode for 30 seconds to return to Visual Voicemail. I have personally experienced the "Call Voicemail" issue every time I have updated to the newest iOS 11 beta and reboot my phone. After two attempts, the Airplane suggestion worked and returned my Voicemail back to normal, where I can read a transcript or listen to an individual voicemail directly from my iPhone. Here's how to quickly enable and disable Airplane mode: Swipe up from the bottom of your display anywhere on the Home screen. Tap the airplane icon. Wait 30 seconds then tap the airplane icon again.
This iOS app does basically the same thing as the above method. It starts a call, initiates a second call, then merges the two so it can be recorded. However, instead of calls being stored in your voicemail, they’re stored in the app. Automatic Call Recorder Pro costs $4.99.

Make sure to keep the microphone in an appropriate angle and distance while recording. When finished, tap “Stop” and finally “Save”.
For those with voicemail greetings that get changed about as often as a new president is elected, know that this is doing a serious disservice to the caller-recipient relationship. It signals to callers that the business is anything but an authority, most likely not very detail oriented, and has questionable overall credibility and competency. Those aren’t traits that any business wants to associate itself.