I figured out a partial solution. *71xxx-xxx-xxxx changes your voicemail number on Verizon.
I have a partial solution working:
1. Set up a new google voice account and e-mail.
2. Added both my work phone and personal phone into the google voice settings.
3. Personal phone is set to receive text message notifications of voicemails.
4. Work phone is not set to receive notifications, but I have installed the GV app.
5. *71'd my new GV number into my work phone.
If I call my iPhone, after four rings it transfers to Google Voicemail. If a message is left, I get a text notification on my personal phone and a GV app notification on the work phone.
I don't see any way to make this selective by business hours, but it is not a big deal to get the occasional extra text throught the day.