I have a Vonage account for my home office line here in Montreal, not so much to save money but for a very specific reason: I live in Canada but all my clients and colleagues are in Washington, DC. Vonage allowed me to set up a virtual phone number in DC so everyone there can reach me with a local call. That's a feature that I haven't seen offered by anyone else: sure, Bell Canada and Videotron (cable) allow me to set up virtual numbers, but only within Canada. Vonage is the only company I know of that lets you set up a virtual number in other countries.
) is operated by Primus, some Canadian outfit.
Lingo offers virtual numbers in all manner of countries. I'm not sure what the business charge is for that, but I could add one virtual number to my home service for $5/month and up, depending on where the virtual number was. I expect that you could get a DC number easily.
Now, if this is out of line for these forums, someone say something: Lingo offers a referral plan where a new customer references an old customer, and if the new customer stays for 91 days, both customers get a $25 service credit. In the early days I went 8 months without being billed. If you need to switch due to Vonage problems, drop me a note and we can set up a referral. Again, if this is out of line for these forums, someone say something and I'll not mention this again.
In my case, Lingo had an extra feature that caught my attention. When I signed up, my no-charge outbound calling area was the US, Canada, and western Europe. I have friends in Canada and one on the edge of the Black Forest in Germany. Since then they've added a few countries.