I often don't have cellular service in my office. Usually when I leave the building I receive voicemail notifications. Now I'm getting them 10-24 hours later. IvI' tried resetting network settings. I've got an original Google Pixel with visual voicemail.
Can you use Wifi calling in the office?
Restarting your phone as soon as you’re within range?
Add to your voicemail a notice to send text or call another number?
Have calls forwarded during work hours?
WiFi doesn't reach my office. I don't have another phone. I restarted my phone after work yesterday. I don't get a lot of voicemails so it may be awhile before I can tell if restarting works. It would be nice if I didn't have to do that. I have worked in my current office for three years and the delayed voicemails only started a few weeks ago.