Computers these days are performing more and more functions that have traditionally been performed in other ways. One example of this is using a computer to make a telephone call. This is called computer-telephone integration, or CTI.

One main form of CTI that gets a lot of press these days is VoIP, or Voice over Internet Protocol. This technology uses an Internet connection and a computer to make a telephone call. VoIP is a form of CTI, but it is by no means the only one. CTI has more traditional forms.

One of the more traditional forms of CTI is when a computer acts as a call center. Computers can take the place of human operators, routing calls from caller to receiver. And it's not just phone calls. CTI allows transmission and reception of FAXes and the aforementioned Internet phone calls. This includes email as well, since the transmission of an email message mimics a phone call. CTI also offers features traditionally found on non-computerized phones, including caller ID, call forwarding, voice mail, and teleconferencing.

Technically, CTI works via a dedicated application which manages phone calls every step of the way. This naturally makes possible archiving and tracking of phone call data, including number called, length of call, charge for call, and so on. Whether the user wants it or not, this data is there for the taking.

In its simplest form, CTI is one person calling one other person and using a computer to route the call. In this case, the CTI application is usually what is called first-person control. The person making the call controls the form and function of the CTI, and the receiver need not have a CTI application or device in order to receive the call.

The most complex form of CTI is a call center, which can handle hundreds, thousands, or even millions of calls a day. Call centers typically have CTI devices and applications everywhere, tracking, facilitating and archiving phone data. This is called third-party control, meaning that neither the calling party nor the receiving party has control of the CTI process but that that control rests in the hands of the call center.