One caveat - if you have medical issues or other reasons that require the ability to summon aid under almost any circumstance, the landline phone is still the most reliable. Even with a UPS for the cable modem (or whatever) and VoIP box, you have limited connectivity - IF your internet stays up. Many cell sites don’t have back-up power and the telcos are fighting a proposed FCC rule that would require only a 4 hour backup power capability. Plus in emergencies the cell sites may be overloaded to boot.
I figure VoIP with cellular backup is good enough for me, but YMMV, just do your homework - it’s not strictly a financial consideration. The landline telephone system has evolved for over 100 years to provide service under adverse conditions, as long as the wires are intact.
I probably would have dumped my landline a long time ago, but after 9/11 I will hang on as long as they let me. Remember how everyone in NYC was trying to get to a landline when no ones cell phones were working.
I can still receive faxes, and messages at home, while I am out, by people I don’t want to have my cell number.