Not a service I'm specifically familiar with, but bigger picture - regardless of using VoIP or POTS or whatever, isn't it just clinging to the old paradigm of having a land line when most people tend to just use their mobile phones?
Well, there are reasons to maintain a landline, especially if you're really, literally paranoid like me.
A mobile phone is a one point fail object. The phone breaks, quits working, gets lost or stolen, you are incommunicado. You can't call for help, can;t be reached if someone is having an emergency, etc.
A landline can be taken out by various things, but can often be quicker and easier to fix.