It may have changed but I used to have Vonage. When you call someone the caller ID says Vonage and not your business name. They wouldn’t change it.
I’ve tried several of the VOIP providers and have had problems with them all. Verizon is supposedly cutting the numbers back to their system tomorrow.
One phone line with call waiting might work for you.
The 800 number has to terminate at a regular local telephone number, so technically speaking, you could get away with the FAX line and just one other telephone number...
I have a HP fax/scan/printer. It’s maavelous and the ink is cheap. I’ve got just a regular AT&T two line plan costs about $57/mo., my U-verse wireless internet connection is $29 and they even threw in my U-verse tv plain package for $20. I have one line for the fax, one for my office line. I’ve got an 800# pointed at my regular line, so I only need two lines. As for phones, since it’s just me all I’ve got is two cradle wireless phone system. I office at home, so I have regular analog lines. If you’re in an office space, you need to find out what kind of phones lines are in there. If it’s just regular analog lines and not hooked up to some elaborate building phone panel with digital service, then just two standard two-line phones you can get for about $100.00.