A soft phone is a computer application that allows users to make telephone calls directly from their computer. A soft phone is most often used in conjunction with Voice over Internet Protocol (VoIP), a form of computer telephony. The soft phone is part of a category of technology known as computer telephony integration (CTI). With a soft phone, calls can be made from the PC to a phone line, from a phone to the PC, or between soft phone-enabled computers.

The software for a soft phone usually mimics the appearance of a real handset and can take the form of either a standalone program with its own window, or an embedded program in a Web application or other PC program. Commands can be entered through either the keyboard or the onscreen interface. Conversations are conducted on a headset with a built-in microphone, with a microphone and the computer’s speakers, or on a USB phone -- a handset that plugs into computers’ USB ports. The computer’s sound card is used to provide audio input and output for the soft phone.

The typical soft phone has all the functionality and features of a conventional telephone, including speed dialing, teleconferencing, call forwarding, and call waiting. Many companies have soft phone programs available to download, but the software alone does not enable users to make calls. A soft phone must be used with VoIP or an existing Local Area Network (LAN). There are several Internet telephony service providers to choose from. The right type of soft phone depends on a user’s needs -- for example, whether the soft phone will be used for business or personal calls.

The soft phone is most popular in business applications. It is well suited for users who want the ability to carry their office phone along with all of its features and directories on a laptop, such as those who frequently use the computer and phone simultaneously and who may be required to travel. Examples include employees of a call center that takes sales or technical support calls. For these users, customer information can be set to display automatically in the soft phone window when the phone rings.

For companies that use predictive dialers to make large batches of calls, a soft phone program can be integrated with their existing system. Many programs can generate reports and graphs displaying information about the call campaign, such as statistics for inbound and outbound calls. Soft phone technology also allows more employees to work from home, offering a potential economic savings to businesses.