Softphone
Encyclopedia
A softphone is a software
program for making telephone calls over the Internet
using a general purpose computer, rather than using dedicated hardware. Often a softphone is designed to behave like a traditional telephone
, sometimes appearing as an image of a phone, with a display panel and buttons with which the user can interact. A softphone is usually used with a headset
connected to the sound card
of the PC, or with a USB phone
.
.
. Many service providers use the Session Initiation Protocol
(SIP) standardized by the Internet Engineering Task Force
(IETF). Skype
, a popular service uses proprietary protocols and Google Talk
is based on the Extensible Messaging and Presence Protocol
(XMPP). Some softphones also support the Inter-Asterisk eXchange protocol (IAX), a protocol supported by the popular open-source software application Asterisk.
, Flash, Hold, Transfer etc) and often additional features typical for online messaging, such as user presence indication, video, wide-band audio. Softphones provide a variety of audio codecs, a typical minimum set is G.711 and G.729.
Computer software
Computer software, or just software, is a collection of computer programs and related data that provide the instructions for telling a computer what to do and how to do it....
program for making telephone calls over the Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
using a general purpose computer, rather than using dedicated hardware. Often a softphone is designed to behave like a traditional telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
, sometimes appearing as an image of a phone, with a display panel and buttons with which the user can interact. A softphone is usually used with a headset
Headset (telephone/computer)
A headset is headphones combined with a microphone, or one headphone with a microphone. Headsets provide the equivalent functionality of a telephone handset with hands-free operation. Headsets typically have only one speaker like a telephone, but also come with speakers for both ears...
connected to the sound card
Sound card
A sound card is an internal computer expansion card that facilitates the input and output of audio signals to and from a computer under control of computer programs. The term sound card is also applied to external audio interfaces that use software to generate sound, as opposed to using hardware...
of the PC, or with a USB phone
USB phone
USBphone looks like a traditional telephone, but it has a USB connector instead of an RJ-11. It may be used with most softphones and services like Skype, Sipnet, Sippoint Mini, Net2Phone, MSN Messenger, NetMeeting, Xlite....
.
Applications
A typical application of a softphone is to make telephone calls on the network of an Internet telephony service providerInternet telephony service provider
An Internet telephony service provider offers digital telecommunications services based on Voice over Internet Protocol that are provisioned via the Internet....
.
Communication protocols
To communicate, both end-points must have the same communication protocol and at least one common audio codecCodec
A codec is a device or computer program capable of encoding or decoding a digital data stream or signal. The word codec is a portmanteau of "compressor-decompressor" or, more commonly, "coder-decoder"...
. Many service providers use the Session Initiation Protocol
Session Initiation Protocol
The Session Initiation Protocol is an IETF-defined signaling protocol widely used for controlling communication sessions such as voice and video calls over Internet Protocol . The protocol can be used for creating, modifying and terminating two-party or multiparty sessions...
(SIP) standardized by the Internet Engineering Task Force
Internet Engineering Task Force
The Internet Engineering Task Force develops and promotes Internet standards, cooperating closely with the W3C and ISO/IEC standards bodies and dealing in particular with standards of the TCP/IP and Internet protocol suite...
(IETF). Skype
Skype
Skype is a software application that allows users to make voice and video calls and chat over the Internet. Calls to other users within the Skype service are free, while calls to both traditional landline telephones and mobile phones can be made for a fee using a debit-based user account system...
, a popular service uses proprietary protocols and Google Talk
Google Talk
Google Talk is a freeware voice over Internet protocol client application offered by Google Inc. The first beta version of the program was released on August 24, 2005...
is based on the Extensible Messaging and Presence Protocol
Extensible Messaging and Presence Protocol
Extensible Messaging and Presence Protocol is an open-standard communications protocol for message-oriented middleware based on XML . The protocol was originally named Jabber, and was developed by the Jabber open-source community in 1999 for near-real-time, extensible instant messaging , presence...
(XMPP). Some softphones also support the Inter-Asterisk eXchange protocol (IAX), a protocol supported by the popular open-source software application Asterisk.
Features
A typical softphone has all standard telephony features (DND, Mute, DTMFDual-tone multi-frequency
Dual-tone multi-frequency signaling is used for telecommunication signaling over analog telephone lines in the voice-frequency band between telephone handsets and other communications devices and the switching center. The version of DTMF that is used in push-button telephones for tone dialing is...
, Flash, Hold, Transfer etc) and often additional features typical for online messaging, such as user presence indication, video, wide-band audio. Softphones provide a variety of audio codecs, a typical minimum set is G.711 and G.729.
Requirements
To make voice calls over the Internet, a user typically requires the following:- A modern PC with a microphone and speaker, or with a headset, or with USBphone.
- Reliable high-speed Internet connectivity like Digital subscriber lineDigital Subscriber LineDigital subscriber line is a family of technologies that provides digital data transmission over the wires of a local telephone network. DSL originally stood for digital subscriber loop. In telecommunications marketing, the term DSL is widely understood to mean Asymmetric Digital Subscriber Line ,...
(DSL), or cable service. - Account with an Internet telephony service providerInternet telephony service providerAn Internet telephony service provider offers digital telecommunications services based on Voice over Internet Protocol that are provisioned via the Internet....
or IP PBXIP PBXAn IP PBX is a business telephone system designed to deliver voice or video over a data network and interoperate with the normal Public Switched Telephone Network ....
provider.
See also
- IP PhoneIP PhoneA VoIP phone uses voice over IP technologies allowing telephone calls to be made over an IP network such as the Internet instead of the ordinary PSTN system. Calls can traverse the Internet, or a private IP network such as that of a company...
- Auto dialerAuto dialerAn auto dialer, autodialer, or autodialler is an electronic device or software that automatically dials telephone numbers. Once the call has been answered, the autodialer either plays a recorded message or connects the call to a live person....
- VoIPVoice over IPVoice over Internet Protocol is a family of technologies, methodologies, communication protocols, and transmission techniques for the delivery of voice communications and multimedia sessions over Internet Protocol networks, such as the Internet...
- Mobile VoIPMobile VoIPMobile VoIP or simply mVoIP is an extension of mobility to a Voice over IP network. Two types of communication are generally supported: cordless/DECT/PCS protocols for short range or campus communications where all base stations are linked into the same LAN, and wider area communications using...
- VideophoneVideophoneA videophone is a telephone with a video screen, and is capable of full duplex video and audio transmissions for communication between people in real-time...
- Computer Telephony IntegrationComputer telephony integrationComputer telephony integration, also called computer–telephone integration or CTI, is a common name for any technology that allows interactions on a telephone and a computer to be integrated or coordinated...
- List of SIP software
- Comparison of VoIP softwareComparison of VoIP softwareVoIP software is used to conduct telephone-like voice conversations across Internet Protocol based networks. VoIP stands for "Voice over IP". For residential markets, VoIP phone service is often cheaper than traditional public switched telephone network service and can remove geographic...