That would be Fios service.
My suspicion is that the telephone number isn't fully set up in Verizon's network/equipment. If it was, calls to the toll-free number or *86 wouldn't reach an error message.
Try power cycling the ONT (unplug the power for maybe 15 seconds & then plug it back in) and try to acess the voicemail system again.
If that doesn't work, contact Verizon Repair and have them check things out on their end.
