The cheapest phone service I've been able to find is Skype on the internet. It costs $3/month to make outbound calls to any phone in the U.S.A. If you want people to be able to call you, you also need to sign up for a phone number at the cost of $12/3 months for the first 3 months (this may go up to $24/3 months afterwards). In addition, you need a headset or you can probably get by with a microphone and speakers. I bought a headset on Amazon.com for $30. Be sure it is advertised (specified) to work with internet phone services.
The phone service includes long distance calls within the U.S.A., voicemail, and email notification of voicemail (love this).
There are four caveats.
First, they are charging my bank card monthly for the $3 although I didn't give them permission to do so. WARNING, it may be difficult to terminate the service and get them to stop the monthly charges on the bank card.
Second, USER BEWARE; the interface is difficult to use, it is counter intuitive. It may take 2 weeks to make sense of it and one month before you can use it without thinking. If you don't consider yourself very computer savvy, do not attempt to use this service.
Third, IT FAILS SOME OF THE TIME. Usually the calls are crystal clear and work perfectly, but I experience problems about 3/week and they come in batches. Possible failures include answering the phone and it doesn't connect, making a call and it doesn't connect when the other party answers, echo that varies from mild to severe, and noticeable delay. I suggest we all report problems with any call so Skype can continue to improve the quality. It is easy to do. There is a call quality feedback button (button with a green symbol on the right) that brings up a list of problems; just select the applicable problem and submit.
Fourth, the ringer setting seems to reset itself sometimes. I set it to ring on the PC speakers, which it does for the day, then the next day it's only ringing on the headset. The only reliable way I've found to hear the ringer is to unplug the headset earphones plug. I'd love to hear from anyone who has solved this setup problem.
The website address is http://www.skype.com/welcomeback/ First, download Skype. Then subscribe for the outbound calls service and phone number service. Sue started using Skype yesterday. How is it going Sue?