An Internet telephony service provider (ITSP) offers digital

telecommunications service A telecommunications company is a kind of electronic communications service provider, more precisely a telecommunications service provider (TSP), that provides telecommunications services such as telephony and data communications access. Many t ...

s based on

Voice over Internet Protocol Voice over Internet Protocol (VoIP), also known as IP telephony, is a set of technologies used primarily for voice communication sessions over Internet Protocol (IP) networks, such as the Internet. VoIP enables Voice call, voice calls to be tran ...

(VoIP) that are provisioned via the

Internet The Internet (or internet) is the Global network, global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a internetworking, network of networks ...

. ITSPs provide services to end-users directly or as whole-sale suppliers to other ITSPs. ITSPs use a variety of signaling and multimedia protocols, including the

Session Initiation Protocol The Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, and terminating communication sessions that include voice, video and messaging applications. SIP is used in Internet telephony, in private IP telepho ...

(SIP), the

Media Gateway Control Protocol The Media Gateway Control Protocol (MGCP) is a telecommunication protocol for signaling and call control in hybrid voice over IP (VoIP) and traditional telecommunication systems. It implements the media gateway control protocol architecture f ...

(MGCP),

Megaco The Gateway Control Protocol (Megaco, H.248) is an implementation of the media gateway control protocol architecture for providing telecommunication services across a converged internetwork consisting of the traditional public switched telephone ...

, and the H.323 protocol. H.323 is one of the earliest VoIP protocols, but its use is declining and it is rarely used for consumer products. Retail customers of an ITSP may use traditional analog telephone sets attached to an

analog telephony adapter An analog telephone adapter (ATA) or FXS gateway is a device for connecting traditional analog telephones, fax machines, and similar customer-premises devices to a digital telephone system or a voice over IP telephone network. An ATA is often ...

(ATA) to connect to the service provider's network via a

local area network A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, campus, or building, and has its network equipment and interconnects locally managed. LANs facilitate the distribution of da ...

, they may use an IP phone, or they may connect a private branch exchange (PBX) system to the service via media gateways. ITSPs are also known as voice service providers (VSP).

History

Usually, ITSPs negotiate agreements for route termination to various parts of the world from multiple VoIP providers. ITSP customers may be able to choose a VoIP provider for their VoIP calls. Customers may be able to do this by specifying the maximum price they are willing to pay per minute for a call and the lowest quality they are willing to tolerate. The ITSP routing software searches for the wholesale VoIP providers who meet the customer specification and attempt to route the customer call to the providers starting with the one have the lowest quoted price. Pricing to different parts of the world depend on several factors, such as the routing via a

white route In telecommunications business, a white route is a route where both source and destination are legal termination. This is opposed to a black route, which is a route that is illegal in both ends. Also common in telecom (especially VoIP) is the ter ...

or a black route, wholesaler's margin, and the country's regulations.

References

{{Telecommunications Voice over IP

History

See also

References