If you are in sales or consulting, live in the USA or Canada and work most of the time from home, you might find the following article on setting up high quality sales communication system worth the time it takes to read.
Selling from a Home Office
I've been working from a home office since 1995 and have had a variety of communication set-ups and have tried a number of different telephone service providers including Pac-Bell, Sprint, Nextel, British Telecom and T-Mobile.
In setting up my new home office, I had planned to use my cellphone as my only phone with T-Mobile— they have an all you can eat voice and data plan that is (un)reasonable...but I'm stuck with it. Unfortunately the signal in my office is very poor and a non-starter for professional communication, so I needed a plan "B".
Quality Matters
When I ordered the Internet service I went to the local cable company, Comcast, as they have upgraded their technology and service level and offer a competitive introductory rate for broadband. I declined their phone service at $60 per month however as I knew I could install VOIP myself for a lot less.
I had used Vonage for six months and Skype for about six years in the UK and tried Skype here for a few months, investing in a high quality USB microphone and a noise cancelling headset, but found voice quality very choppy and plenty of times would just get cut off or the sound quality was not good enough for sales conversations.
It's hard enough to get someone on the phone — when you do, static on the line and garbled communication is intolerable. I was spending about $40 per month on the Skype service and was not happy with service, although Skypetogo was useful in speaking with overseas family members on my cellphone for the price of a local call when out of the office on my cell.
Ooma Telo
I did some homework on DECT phones
to connect to the VOIP 
system and went my local BestBuy to buy a set and get a couple of recommendations on VOIP. After more homework I opted for the Ooma Telo VOIP system at the basic level and paid just over $200 for the device. The Ooma Telo system (pictured) gives you unlimited phone calls in the US and you pay a fee in advance for International calls at similar International rates to Skype (1.5 cents/minute), but there is no monthly fee, except for local taxes - about $3.00 per month in my case.
Integrated Bluetooth Headset and Mobile
I bought a Bluetooth enabled Panasonic KX-TG6581 DECT 6.0 
system with a desk unit and 2 handsets...this is a great phone, optional upgrades are a DECT repeater and extra handsets.
Already the owner of the excellent over the ear Plantronix Voyager Pro Bluetooth headset with a boom 
microphone, I paired this with the handset.
I installed the Ooma system, connected up the DECT phone in about 10 minutes and after the new number was provisioned, started making calls within an hour....crystal clear calls.
I've had the system for over 9 months now and the quality is excellent most of the time (which is the same for most VOIP providers), my cell phone usage has dropped in half and I have renegotiatied my rate down with T-Mobile. The ROI on this total investment was less than 6 months. If I had been using Comcast phone services my ROI would have been less than 3 months. The Bluetooth on the Panasonic supports my Android mobile phone so that when a call comes in on my mobile I can pick it up on the Panasonic DECT system.
Take-aways
1. There is no room for compromise in quality of your voice communication when selling over the phone .
2. The Ooma Telo system works great and will pay for itself in months.
3. Bluetooth headsets have come a long way and I wear the Voyager Pro all day...I dont even notice it is there.
4. The Panasonic DECT 6.0 phones have a long battery life, work extremely well with Bluetooth and have everything you need.
Addendum
Since writing this article I have added my old Polycom Soundpoint Pro
speakerphone into the mix as I record a lot of my whiteboard messaging conference calls and wanted the best possible audio reproduction. I simply added a split jack onto the analog port on the back of the Ooma.
The sound quality on this analog speakerphone is unbeatable.
I also highly recommend the Roland R-05 voice recorder from The Sound Professionals. I have bought a ton of professional recording gear from them over the years and found them to be an excellent source of high quality gear and sound advice. 
The one in the image has superseded the unit I am using, but I use it in nearly every meeting as it is extremely valuable to have a recording to refer back to when a reference is needed and weeks have passed since the conversation.
Sennheiser is excellent and as it plugs into my Polycom, I have complete control over the volume. Don't forget to order the quick release adapter cable to connect the headset into the phone and this will vary depending on whether you are connecting into the analog jack on the back of the phone or the headset jack.
