Did we say free? Well, kind of.
You see, the geniuses at ObiHai designed a box that takes Google's free calling, and a free Google Voice number, and routes it into a normal phone. Pay for the Obi box, which is $30-$70, depending on the model, and you have free phone service for as long as Google Voice remains free.
How much is your monthly office phone bill? $100? $200? Extrapolate that over a year or two and the saved overhead is truly significant.
If you aren't familiar with the majesty of Google Voice yet, you should be. It's as simple as Gmail, yet far more useful. It uses the standard Google interface but assigns you a phone number in your chosen area code (you can even search for numbers based on words, like 530-iCHUNKY).
That number will route incoming calls to your cell phone, home phone, or office phone, plus allow you to send and receive texts, make calls through your Gmail inbox, and route outgoing calls from your cell phone through the GV number. The caller sees your GV number instead of your cell number, which means no late night calls from crazy clients.
There are three models: the 100, 110, and the 202. Each acts as a bridge between a regular telephone and Google Voice, allowing that phone to act as any other landline would. The 110 also allows you to bridge a local landline in as well, in case you want to make 911 calls or keep a hard-wired line in case of Internet outages.
The 202 is the real gem, however. You can hook up two GV accounts and it will act as a multi-line switch, just like your old fashioned multi-line landline setup. It's probably worth the extra $20 or $30 bucks for the second line capability alone. The device also has a built-in internet priority (QOS) manager, which ensures that your voice calls get higher bandwidth priority than your associate's YouTube videos of cavorting puppies.
We alluded to it already, but there is no 911 calling. This is a typical fault with VOIP services. If you need to dial 911, you'd better have your cell phone handy. Then again, who doesn't keep their cell phone attached to them at all times?
Also, this may be obvious, but if your Internet goes down, so does the phone service. The voice connection is carried over the Internet instead of phone lines. With today's always-on Internet connections, how often do you lose connectivity anyway? Even if you do, Google won't, so you'll still get voicemails.