The widespread use of high bandwidth, always on, connections ot the
internet has enabled the use of one's internet connection to provide
phone service to the home. There are several kinds of internet phone
services to consider. Among these, the most reliable systems are
those provided by the cable company (if you have cable modem service),
or through FiOS or uVerse, where the connection to the phone network
is made locally, you have a dedicated network between the head end,
and your phone interface box, and you do not typically need to worry
about problems with internet connectivity due to congestion or routing
problems. These options will cost you close to the amount you would
pay for wided phone service, with some discounts for bundling with
television and internet.
Your other options involve routing the packets for your phone service over the open internet, with services such as Skype, Ooma, or Vonage.
SkypeAccording to the Skype review on the hmtecch.info site, Skype provides extremely high quality PC to PC voice calls, videoconferencing capabilities, as well as the ability to obtain a phone number so that others can call you over your internet connection. PC accessories are available that will provide a more common telephone receiver through which you can make and receive phone calls. You can also use a simple headset or even the speakers on your PC itself, without extra accessories. The quality of calls to and phone tradition telephones is of lower quality than the PC to PC calls, but this is a limitation of the basic phone system, rather than of skype itself.
VonageThe Review of Vonate on the hmtecch.info site indicates that Vonage provides a "local dial tone", i.e. a phone number where those on the basic phone system can reach you. You receive a Skype modem that connects to your telephone receiver, so that your phone rings when other call you, and you can pick up your phone and hear a dial tone, and you can dial any phone in the US for free (on they standard unlimited plan). Call quality for calls to "landlines" is comparable to Skype. You can expect to pay around $25 (plus taxes) per month for the Skype service. There are less expensive and more expensive plans as well.
OomaThe Ooma service takes a slightly different approach to providing your monthly phone service, i.e. an approach that is not monthly. Instead, you by the Ooma Hub for around $250, hook it up to your internet connection, and receive a phone number and unlimited calling within the US for free thereafter. They have apremier service for $100 per year, which gives you a second number, three way calling, and other useful services. I have heard that the quality of calls using Ooma is slightly better than that of Vonage. I have been using Ooma for several months and am completely satisfied.
Voicemail servicesVoicemail services are discussed on Voicemail services are discussed on the mailbox page in the section on voicemail.