This is my Personal and professional view point, as a VOIP network Admin and business consultant for 22+ years now, and a Vonage user for 5+ years, we even run our own in house SIP servers.
     Grandaccess Services through Vonage offers its customers outstanding digital phone service at an affordable price. Unlimited calling in the United States & Canada and many other countries is only $24.99/month, Plus a ton of other services included for FREE, and requires no line from the local phone company.

     Vonage is offering some pretty good sign up bonuses right now for new customers and even if you were to get their service on the web from an advertisement or at best buys or any store that sells them, you would get a good deal.
     But sometimes they give offers that are by invitation from personal or businesses so we can offer good deals to our friends and family or customers

Topic and points of Vonage and VOIP (Voice Over Internet Protocol)
    Pros and cons of VOIP and Vonage From a Computer/ Internet consultant ...

     Cons? well after 5+ years on their service and Very happy with them! there are not to many that I can think of but
"if " there is one I will list it in each area, If you have any questions that you would like me to clear up please feel free to email me any time.

What you need to get started:
    Cable or DSL Internet or higher T-1 etc.... it will not work on Dial-up sorry..... Also will not work on Satellite for two reasons 1) the delay is to long "7 seconds in most cases" 2) IP is translated into a Satellite only language and back to IP
Pros: In this Internet day most Americans have high speed access "Cable Modem or DSL" so there is a good chance you are ready to roll!
Cons: If you have DSL you have copper to the house anyway and cant cut out the phone company, but can still be cheaper And you will get better service and more functions then the POTs "plain old telephone service" The long Distance service alone saves us $500+ per month alone (This is a no-brainer!)
     Its so simple any one can hook it up and use it! 1) plug the power in 2) plug in the ATA device into your Cable or DSL modem 3) plug your standard home phone into the ATA device EASY!
     Yes with Vonage its that easy! you simply plug your phones into a small device called an Analog Telephone Adaptor (ATA), When you pick up a phone, the ATA gives you the same dial-tone you're used to, and you dial any number just as you would when using the local telephone network (POTS Line).

Outages?
    Outages do not generally occur because of Vonage or their equipment, they may because your cable or DSL goes down or maybe a power failure, tree across a line somewhere that brings down your cable or DSL line, but that would happen with your regular hard line phone line anyway.....
     We use UPS power backups from APC so even if there is a failure we have some standby time.
    There is a Pro to this with Vonage! if Vonage loses contact with your ATA device it will reroute your call to what ever phone number you chose ie: cell phone We actually Love that part of the service for two reasons if we are out (or even out of the country) after three rings it rings over to our Cell, if we go on vacation and take our Vonage with us ... as we are in transit phone calls go right to our cell, if we don't pick up it goes back over to vonage voicemail!

Quality of Sound:
    100% Great, its not the VOIP you have heard in the past, we have all heard bad or cheap VOIP garble and all those that go through the computer first (that also tie you to a computer headset) Skype etc....
    No, we have now had our vonage box on all the above connections and do not see a difference in sound quality ie: Cable, DSL and now we are on a Commercial connection T-1 through AT&T no one in 5+ years has ever been able to notice we were running VOIP!
    Not Just real good but I believe to be better them POTs by far!
Cons: sometimes Cable and DSL limit your bandwidth both incoming and out going so if you are downloading a Movie or using Limewire to get songs you may hear some degradation in voice quality but that's easy to remedy :)

Some States and services:
    We have heard that some ISPs are putting limits on services they don't provide (they want you on their service) so they degrade others, I have heard in California they have it locked down to you getting only the ISP provided VOIP We think that's not right and there has to be a work around .....(get around it some how)

Take it with you anywhere
    When you plug in your ATA phone device it uses DHCP to get its IP address and sets itself automatically and lets the service know its on and where to send calls to (its pretty simple actually) most of the time it comes with its own router that provide this DHCP so all you have to do is plug it in to where ever you go with Internet on cable or DSL and your ready to get and make calls
    To let you know how we use it we are on the road a lot and visit friends and family all over the east coast and we can take our phone and number with us! we have a house in another state and when we go we plug it into the Cable and no one even knows where we are because you pick up the phone just like you would at home or office!
Cons: I don't see any .... other then maybe the 911 issue :)

Other service we use:
    This is the coolest part of Vonage! we have local phone numbers in different states like a 678-Georgia number and a 607-Binghamton, NY number and an 800-Toll Free number and they all ring to our one device right here, you can have as many as you want in any area code and also over seas phone numbers also like London :)
    I also don't like calling for my voice mail so I have Vonage set to send me the .wav file to my email that makes it so easy for me, or if your out and check your email
     A Grand Phone Service, With Vonage, extra features do not cost anything extra -- everything is included in one package. Along with unlimited local and long-distance calling to the U.S. - Canada, and free to many other countries you get:

Free Personalized Voicemail
Free Call Transfer
Free Caller ID with Name
Free Caller ID Block (*67)
Free Call Waiting
Free Call Return (*69) 
Free 3 Way Calling
Free International Call Block
Free Call Forwarding     
Plus many other included services!
Phone Number Portability - Take your ATA with you when you travel, plug it into any Internet connection, and your phone calls will follow you wherever you go.
Area Code Selection - Choosing an area code from any state or even from another country. Make your  2nd number a local call for friends or family in another state. Discounted Additional Lines and Virtual Numbers - Setup a number in almost any state or country, forwarded to your primary number

Email Message Notification - have the system send you an email when someone leaves a message in your voicemail box, and retrieve that message by phone or over the Internet.

Great International Rates - Call overseas for as little as $0.05 per minute.
Click here for a complete list of our international rates.

E-911 and 911 Service Locator Pros and cons for any VOIP service
    They need to know where you are so they can send help! Normally when you call 911 you show up on their screen who, what, where now days even if you are calling from a cell phone they have your Lat/Long, VOIP is no different.
     One of the first things you do when you get your new service through Vonage is log into your account on their web site and set all your Preferences like no answer transfer and voice mail prefs on one of the pages you fill out information on your location so that when you dial 911 they know its you and where to go, so every thing you have heard in the media is Crap just like every thing else you hear from the media
    Cons: if you take it with you like we do, and you happen to call 911 .... we they are going to go to your registered address! But like me if we were to ever call 911 it would be from our Cell Phone anyway
Vonage 911 operates differently than traditional 911. E911 and not available everywhere.

Patent Infringement? Verizon and the rest of the VOIP industry
     We will be keeping a close eye on this situation but I don't feel it will have a long term impact on any ones VOIP service, Vonage is not the only one that will be affected by Verizon and Vonage being sued they are just the first, the same Patent Infringement could affect every VOIP service not just Vonage, so this is just the tip of the iceberg! I think Verizon is being stupid and it will cause a failure in VOIP tech moving forward, the way the judge should see it as a National Security issue and any ruling of such would ruin trust in the tech industry

Broadband Voice Gateway SIP (Session Initiation Protocol) / IP / CGP
     The Session Initiation Protocol (SIP) is an application-layer control (signaling) protocol for creating, modifying, and terminating sessions with one or more participants. These sessions include Internet telephone calls, multimedia distribution, and multimedia conferences. It is widely used as a signaling protocol for Voice over IP, along with H.323 and others.

All around Pricing: You cant lose, its a Money back Guarantee -
    Put it on paper like we did, any way you look at it .... its a savings! lets take Cable if you already have it their special is not all that special $45 for Internet, $45 for Cable CHs and $45 for their VOIP (that's not as good) Vonage is a better service that offers more options for almost half!
      Now DSL costs about the same in most areas about $45 and if you cut out the phone service and long distance you would save a ton of money and better yet not be giving it to the greedy bastards that charge and extra $1 for this and $2 for that and by the end jack you to $50 and not even give quality of service.
     Its the Best Deal they have allowed us to offer! so email us now and we will send you an invitation! If you still have questions please feel free to call or email and we will talk with you about you or your companies situation on a one on one personal level .....
     As a side note to pricing ..... even if it were to cost more, I would still have Vonage!