Are there different kinds of VoIP services?

Voice over IP is still an emerging technology and that means it is still changing in many ways. And, yes, there are many different ways to use VoIP. These include:

Computer-to-computer: Two parties in different locations speak to one another as each sits at a computer. This kind of VoIP connection has existed almost as long as the internet itself. Usually, both sides of the connection are using a headphones and a microphone (though you can use a computer's built-in microphone and external speakers, this usually causes an echo as what comes out of the speakers gets fed right back into the mic and severely disrupts a conversation). Think of this kind of use of VoIP as a modern day version of two cans and a string.

Computer-to-phone: This kind of connection is pouplar among those who make a lot of international calls. There are a number of services that offer overseas calling for just pennies a minute. The way it works is that you use your computer (again, with headphones and a mic is preferred) to log into a server, which then uses a VoIP connection to a regular landline phone exchange abroad, which then connects you to the number you want to reach.

SIP-to-SIP: This method allows telephone calls between two parties while totally bypassing the standard landline telephone system. Each end of a SIP-to-SIP call can use a specialized SIP phone (from companies such as Granstream, and others), a regular handset connected to an internet telephony adaptor, or a computer running softphone software. Companies such as SIPPhonbe offer SIP-to-SIP service.

Phone-to-phone: This method allows the use of VoIP service to contact any other telephone number, even one on the traditional landline service. Companies like Packet8, VoicePulse and Vonage offer this service.