Telephony software clients are the focus of topics highlighted in this category, particularly that used in Internet telephony.
In a general form, telephony refers to the entire field of technology that involves the development and application of telecommunications to transmit voice, fax, or data between parties at remote locations. Early implementations of the technology include the invention of the telephone and telegraph.
Today, the term is more commonly used in reference to the computer software, hardware, and network systems that perform functions traditionally performed by the telephone system, and that's the sense in which we will be using the word in this category.
Fewer than fifty percent of US homes, today have landline telephones, as PC-based telephony is becoming more widely used for communications. Internet telephony refers to the software and hardware products that allow users to use their Internet connections for voice and data communications. With the dominance of fixed-price Internet access, Internet telephony software gives the user free telephone calls anywhere in the world, as it is paid for in the cost of the Internet service.
There are three main categories of Internet telephony. These are PC-to-PC telephony, PC-to-phone telephony, and phone-to-phone telephony.
Through computer-to-computer (PC-to-PC) calling, the client software converts voice into data packets, then routes it over the Internet to the receiving client, which turns the data packets back into voice signals that are transmitted through speakers or headphones on the receiving end.
PC-to-phone telephony allows calls to be made from a user's computer to a regular telephone. This is similar to PC-to-PC calling, but it is a service that a user pays for, although it is less expensive than a traditional long-distance telephone provider. PC-to-phone service requires the same equipment as with PC-to-PC.
With PC-to-phone, the computer is the originating gateway, converting voice into data packets, which are sent through the Internet. At the receiving end, the software converts the data packets back into voice signals that are routed through the regular telephone line.
Phone-to-phone calling is the most recent form of Internet telephony. It allows telephone calls to be placed over the Internet, but without requiring special software or even a computer; rather, it uses traditional telephones on both ends.
Phone-to-phone telephony requires an Internet Telephony Service Provider (ITSP), which will have gateways in various places around the world. When a call is placed through a phone-to-phone telephony service, voice is digitized, compressed, and converted into data packets, which are sent over the Internet to the gateway nearest the receiving party. There, the packets are converted back into voice and sent the rest of the way through traditional telephone lines. Because most of the transmission is over the Internet, phone-to-phone telephony is cheaper than traditional telephone service.
Voice over Internet Protocol (VoIP) is a technology that delivers voice communications over IP networks, such as the Internet. IP telephony, Internet telephony, broadband telephony, and broadband phone services, are terms for the technology that involves the transmission of voice, fax, voice messaging, and SMS over the public Internet, as opposed to traditional wired telephone services. The technology involved in VoIP is similar to that of traditional telephone services except that, rather than being transmitted over a circuit-switched network, the digital information is bundled into packets and transmitted over a packet-switched network.
Methods of VoIP include specialized VoIP phones, which resemble traditional phones but work differently. VoIP is also available through personal computers and other devices with Internet access. Calls and SMS text messages can be sent through mobile data or Wi-Fi. VoIP consolidates modern communications technologies into a unified communications system.
Software and services relating to telephony clients are the focus of this category. However, the focus of this category is on the software. VoIP services should be listed in the VOIP category within the Technology section of the Business & Industry tree.
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3CX is an international VoIP IPBX software developer that markets an open-standards, software-based PBX system available for Windows, Linux, and Cloud-based platforms, and which can be integrated with multiple CRM systems. The system may be self-hosted or operated on Windows or Linux systems and, as it is an open platform, users can choose their own IP phones and SIP trunks. Sold through channel partners, a trial license is available on request.
https://www.3cx.com/
Sponsored by Digium, Asterisk is an open-source framework for building communications applications, powering IP PBX systems, VoIP gateways, conference servers, and call centers. The open-source produce and source code may be downloaded from the site. Also available is Switchvox, an Asterisk-based commercial PBX, and IP phones for Asterisk with full-color displays and multiple lines. Its products and services are highlighted, and a community support forum is included.
http://www.asterisk.org/
Bayonne is the telephony server of GNU Telephony and the GNU Project. Developed in 1998, Bayonne offers free, scalable, media-independent software environment and implementation of telephony in current and future telephone networks. The software is distributed with several Linux implementations and may be downloaded from various sites under the terms of the GNU General Public License. An introduction to the software is provided, along with documentation.
https://www.gnu.org/software/bayonne/
IHU is a Voice over Internet Protocol (VoIP) application for Linux, using Qt, which creates an audio stream between two computers, with minimal traffic on the network. It offers peer-to-peer communications between two computers, supporting UDP and TCP, without the need of session protocols. It also offers good audio performance, and is compatible with ALSA and JACK, using Speex for audio compression. Options are available for encrypting or decrypting the stream.
http://ihu.sourceforge.net/
Developed by the Mumble VOIP Team, Mumble is a voice-over IP application designed primarily for use by gamers, similar to programs like TeamSpeak. The application uses a client-server architecture that allows users to communicate with one another through the same server and features a simple administrative interface. The cross-platform client is free and open-source software made available under the terms of the new BSD License. Documentation is included.
https://wiki.mumble.info/
PC-Telephone is a communications software application that provides PC telephony, allowing users to make free PC-to-PC phone and fax calls over the Internet, LAN, or VPN, along with cheap PC-to-phone calls, PC-to-fax calls, international calls over SIP, and phone and fax calls from the user’s computer over ISDN. The company integrates the computer telephony and VoIP in a single user interface. Its features are available, and free PC-phone software can be downloaded from the site.
http://www.pc-telephone.com/
Offered through open-source (GPL) and a proprietary license, PJSIP is a multimedia communication library that implements standard-based protocols, like SIP, SDP, RTP, STUN, TURN, and ICE, and combines signaling protocol (SIP) with multimedia framework and NAT functions to create a portable multimedia communication API for most computer platforms. The open-source version may be downloaded from the site, which includes licensure data, documentation, and datasheets.
https://www.pjsip.org/
Skype is a telecommunications application that specializes in facilitating video chat and voice calls between computers, mobile devices, consoles, and smartwatches, using the Internet as the medium. Skype also provides instant messaging services and video conference calls. Developed by Skype Technologies, a Microsoft Company, the application operates through the Windows, macOS, Linux, Android, iOS, Windows Phone, HoloLens, and Xbox One platforms.
https://www.skype.com/
In business since 1987, and headquartered in New York, SpeechSoft develops and sells telephony automation software, and offers hardware and turnkey solutions that integrate with various telephony environments, such as VoIP, T1, Digital PBX, and Analog. Thirty-day trials are available for download, along with client testimonials, online and other support services, license agreements, and a list of available products. Brochures, installation guides, and documentation are included.
http://www.speechsoft.com/
VOCAL’s VoIP software includes adaptive jitter and voice quality enhancement algorithms with strong noise reduction, echo cancellation, and dereverberation, as well as VoIP encryption through SIP, SRTP, SDES, IPsec, and other secure protocols, and fully integrated and configurable software libraries, an SIP client and server with Network Stack and a wide selection of VoIP vocoders. Its features are listed on its site, along with its interoperability features and modules.
https://www.vocal.com/software-modules/voip-software/