Vonage is probably the most well known for VoIP telephony services.

You can check out more information or even buy this top rated service (one of the most popular VoIP Services, if not the most) here:

Vonage VoIP

They have 4 main VoIP packages. Plus, you get 1 MONTH FREE if you decide to sign up.

Their Features are as follows:

Residential Premium Unlimited Plan

• “Unlimited local and long distance calling anywhere in the US, Canada, and Puerto Rico. NEW! FREE calls to select European countries!”
• $24.99/month

Residential Basic 500 Minutes Plan

• “500 minutes of local and long distance calling anywhere in the US, Canada and Puerto Rico. Only 3.9¢ per minute after the first 500 monthly minutes.”
• $14.99/month

Small Business Premium Unlimited Plan

• “Unlimited local and long distance calling anywhere in the US, Canada and Puerto Rico for business customers. NEW! FREE calls to select European countries!”-” Plus get a free, dedicated fax line.”
• $49.99/month

Small Business Basic 1500 Minutes Plan

• “1500 minutes of local and long distance calling anywhere in the US, Canada and Puerto Rico for business customers. Only 3.9¢ per minutes after the first 1500 monthly minutes. Plus get a free, dedicated fax line.”
• $39.99/month

The standard features included in each of the packages include:

• Voicemail Plus
• 311 Dialing
• Call Forwarding
• Call Transfer
• Call Hunt
• Area Code Selection
• Vonage V-Forecast
• 511 Traveler Information
• Vonage Moves With You
• Caller ID Block
• 3-Way Calling
• In-Network Calls
• 811 Dialing
• Keep Your Phone Number
• Caller ID with Name
• Call Waiting
• Call Return
• Repeat Dialing
• International Call Block
• V-Access
• Ring Lists
• Click-2-Call

Some Services that may need clarification as to what they are:

• In-Network (as well As V-Access)calls allow you to call any Vonage service user at no extra costs for either party- including 800 and toll free numbers.
• Call-Return allows you to dial *69 to call back the last number dialed to you.
• V-Forecast allows you to check weather conditions and 5 day forecasts in local areas.
• Call hunt is rather hard to explain… Quote from site says “deal for small businesses with multiple Vonage lines, Vonage Call Hunt rings up to 10 Vonage lines in sequence when the main line is busy. The call continues through a list of lines until somebody picks up live. You decide which lines ring, in which order. If the incoming call rings through the last line in your sequence and it’s still unanswered, it’s routed to the Voicemail Plus mailbox for whichever line you designated.”
• Click-2 Call is for computer calling with just a click, broadband connection, and some software.

Plus, you get 1 MONTH FREE if you decide to sign up.
You can check out more information or even buy this top rated service (one of the most popular VoIP Services, if not the most) here:

Vonage VoIP

Most of this information was found on their main site.