When I first started my business (Orbisius which started as WebWeb.ca) I made the conscious decision not to get a phone number from a local provider (with the exception of my cell phone provider) because that would lock me in on a contract and I wouldn't be fully location independent.
The numbers I have are:
2 Canadian phone numbers - Toronto & Niagara area code
1 Fax number (which I no longer use)
Back in 2005-2006 Skype started offering US phone numbers so I picked one and I kept using it to this day.
The quality is good but it lacks some important business features like sending the voicemail to an email and downloading it.
For my Canadian numbers I decided to use http://voip.ms
Voip.ms is a very powerful service but requires technical knowledge and patience to figure out how to best use it but it's worth it.
They send you the voicemails as an attachment (in .wav format, yep I know mp3 would've been better).
There are ring groups and some other rules that you can define when to receive the phone call and when to go to voicemail. I am problably using 5% of the service but it works for me.
When somebody calls it rings on my computer.
I made one mistake before I ordered my Niagara phone number: I should've at least Googled the number as it turned that it belonged to a funeral home (!) so I kept getting calls/faxes which was pretty annoying.
About the fax service I used PamFax with a Toronto area code.
I used the service for 2-3 years and cancelled it because I wasn't using it that much.
I am sure there are other providers. Let me know your experience or lessons you've learned.
Good luck with your business.