As some of you are involved in ventures that may need a small, cheap, professional, pbx-like commercial phones system this is worth a post. I've been on the Ooma residential system since 2007-ish. Works great. Recently, Louise's real estate office's commercial VOIP service had an unresolved failure and I went looking for a replacement, recalling that I'd seen an ad for Ooma's relatively new commercial system.
http://www.smallbusinesscomputing.com/ProductReviews/Hardware/small-business-phone-system-review-ooma-office.html
It uses a proprietary, wireless system to communicate between the base station and phone handsets (150' max range). Any cheap analog phone works, they used this phone in one of the reviews so that's what we're going with for now:
AT&T CL2909
http://www.amazon.com/AT-CL2909-Corded-Speakerphone-Waiting/dp/B001S2PKPE
Another review:
http://www.businessnewsdaily.com/7818-best-phone-system-small-office.html
Seems to work, though there was apparently a glitch in the firmware related to call forwarding --now supposedly resolved. This was mostly plug-n-play. Monthly fees for 1 phone number ported, 2 incoming lines (5 out) with 2 extension numbers is said to be $30, we'll see (but Ooma has been straightforward with our personal acct, so I'm not expecting any predatory behavior). To give a comparison, I'd estimate a business landline with a comparable pbx would be $300-450/mo including amortized equipment & installation costs.