SIP trunking is a
voice over Internet Protocol
Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Internet t ...
(VoIP) technology and streaming media service based on 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) by which
Internet telephony service provider An Internet telephony service provider (ITSP) offers digital telecommunications services based on Voice over Internet Protocol (VoIP) that are provisioned via the Internet.
ITSPs provide services to end-users directly or as whole-sale suppliers to ...
s (ITSPs) deliver telephone services and
unified communications
Unified communications (UC) is a business and marketing concept describing the integration of enterprise communication services such as instant messaging (chat), presence information, voice (including IP telephony), mobility features (including e ...
to customers equipped with SIP-based
private branch exchange
A business telephone system is a multiline telephone system typically used in business environments, encompassing systems ranging in technology from the key telephone system (KTS) to the private branch exchange (PBX).
A business telephone syst ...
(IP-PBX) and unified communications facilities. Most unified communications applications provide voice, video, and other streaming media applications such as desktop sharing, web conferencing, and shared whiteboard.
Domains
The architecture of SIP trunking provides a partitioning of the unified communications network into two different domains of expertise:
* Private domain: refers to a part of the network connected to a PBX or unified communications server.
* Public domain: refers to the part of the network which allows access into the
public switched telephone network
The public switched telephone network (PSTN) provides Communications infrastructure, infrastructure and services for public Telecommunications, telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that ...
(PSTN) or
public land mobile network
In telecommunication, a public land mobile network (PLMN) is a combination of wireless communication services offered by a specific operator in a specific country.3GPP TS 21.905 https://www.etsi.org/deliver/etsi_tr/121900_121999/121905/15.00.00_6 ...
(PLMN).
The interconnection between the two domains must occur through a SIP trunk. The interconnection between the two domains, created by transport via the
Internet Protocol
The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet.
IP h ...
(IP), involves setting specific rules and regulations as well as the ability to handle some services and protocols that fall under the name of SIP trunking.
The ITSP is responsible to the applicable regulatory authority regarding all the following law obligations of the public domain:
* Tracking traffic;
* Identification of users;
* Implementation of the
lawful interception Lawful interception (LI) refers to the facilities in telecommunications and telephone networks that allow law enforcement agencies with court orders or other legal authorization to selectively wiretap individual subscribers. Most countries require ...
mechanisms.
The private domain instead, by nature, is not subject to particular constraints of law, and may be either the responsibility of the ITSP, the end user (enterprise), or of a third party who provides the voice services to the company
Architecture
Each domain has elements that perform the characteristic features requested of that domain, in particular the result (as part of any front-end network to the customer) is logically divided into two levels:
* The control of access (Class 5
softswitch
A softswitch (''software switch'') is a call-switching node in a telecommunications network, based not on the specialized switching hardware of the traditional telephone exchange, but implemented in software running on a general-purpose computing ...
);
* Network-border elements
that separate the Public Domain from the Private Domain, implementing all the appropriate ITSP phone security policies.
The private domain consists of three levels:
* corporate-border elements that separate the public domain from the private domain, implementing the appropriate company security policies
* central corporate switching node
* IP PBXs
See also
*
Trunking
In telecommunications, trunking is a technology for providing network access to multiple clients simultaneously by sharing a set of circuits, carriers, channels, or frequencies, instead of providing individual circuits or channels for each clie ...
*
Session border controller
A session border controller (SBC) is a network element deployed to protect SIP based voice over Internet Protocol (VoIP) networks.
Early deployments of SBCs were focused on the borders between two service provider networks in a peering environme ...
(SBC)
References
{{reflist
Telecommunication services
VoIP protocols