A GPRS roaming exchange (GRX) acts as a hub for General Packet Radio Service (GPRS) connections from roaming users, removing the need for a dedicated link between each GPRS service provider. It was developed to facilitate a more efficient way for operators to interconnect networks, and played a large part in the transition to third-generation systems.
Initially GPRS roaming was based on complicated relationships between individual operators with each operator requiring a dedicated link to each different partner so that , whereby is the number of global operators that would require a dedicated link. This meant that mobile subscribers who wanted to use GPRS whilst roaming could only do so if their operator had a direct agreement with the operator in the country or area in which they were roaming.
In 2000 the GSMA (GSM Association) developed the idea of GRX to handle all roaming between public land mobile networks (PLMNs). [1]
Usually, GRX is based on a private or public IP backbone and uses GPRS Tunnelling Protocol on the session layer (OSI Layer Five) between the visited PLMN (Public Land Mobile Network) and the home PLMN. Each GRX operator will have a network consisting of a set of routers and links connecting to the GPRS networks, moreover the GRX network will have links connecting to other GRX nodes in peer model.
The GRX operator can therefore act as a hub, allowing a GPRS subscriber to interconnect with many roaming partners without the need for dedicated links. For operators this is advantageous in that it allows quicker implementation of roaming partners, faster time to market for new operators and lower capital expenditure seeing as it is a scalable solution depending on bandwidth and quality of service requirements. Because the interconnection between the visited PLMN and home PLMN uses private GRX networks there is also no need to maintain Internet Protocol Security (IPsec) tunnels over the public internet.
The Global System for Mobile Communications (GSM) is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation (2G) digital cellular networks used by mobile devices such as mobile phones and tablets. GSM is also a trade mark owned by the GSM Association. GSM may also refer to the Full Rate voice codec.
General Packet Radio Service (GPRS), also called 2.5G, is a packet oriented mobile data standard on the 2G cellular communication network's global system for mobile communications (GSM). GPRS was established by European Telecommunications Standards Institute (ETSI) in response to the earlier CDPD and i-mode packet-switched cellular technologies. It is now maintained by the 3rd Generation Partnership Project (3GPP).
Short Message/Messaging Service, commonly abbreviated as SMS, is a text messaging service component of most telephone, Internet and mobile device systems. It uses standardized communication protocols that let mobile devices exchange short text messages. An intermediary service can facilitate a text-to-voice conversion to be sent to landlines.
The Universal Mobile Telecommunications System (UMTS) is a third generation mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP, UMTS is a component of the International Telecommunication Union IMT-2000 standard set and compares with the CDMA2000 standard set for networks based on the competing cdmaOne technology. UMTS uses wideband code-division multiple access (W-CDMA) radio access technology to offer greater spectral efficiency and bandwidth to mobile network operators.
In telecommunication, a public land mobile network (PLMN) is a combination of wireless communication services offered by a specific operator in a specific country. A PLMN typically consists of several cellular technologies like GSM/2G, UMTS/3G, LTE/4G, offered by a single operator within a given country, often referred to as a cellular network.
Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for voice calls, the delivery of voice communication sessions over Internet Protocol (IP) networks, such as the Internet.
Roaming is a wireless telecommunication term typically used with mobile devices, such as mobile phones. It refers to a mobile phone being used outside the range of its native network and connecting to another available cell network.
The GPRS core network is the central part of the general packet radio service (GPRS) which allows 2G, 3G and WCDMA mobile networks to transmit Internet Protocol (IP) packets to external networks such as the Internet. The GPRS system is an integrated part of the GSM network switching subsystem.
Mobility management is one of the major functions of a GSM or a UMTS network that allows mobile phones to work. The aim of mobility management is to track where the subscribers are, allowing calls, SMS and other mobile phone services to be delivered to them.
Network switching subsystem (NSS) is the component of a GSM system that carries out call out and mobility management functions for mobile phones roaming on the network of base stations. It is owned and deployed by mobile phone operators and allows mobile devices to communicate with each other and telephones in the wider public switched telephone network (PSTN). The architecture contains specific features and functions which are needed because the phones are not fixed in one location.
GSM services are a standard collection of applications and features available over the Global System for Mobile Communications (GSM) to mobile phone subscribers all over the world. The GSM standards are defined by the 3GPP collaboration and implemented in hardware and software by equipment manufacturers and mobile phone operators. The common standard makes it possible to use the same phones with different companies' services, or even roam into different countries. GSM is the world's most dominant mobile phone standard.
Customized Applications for Mobile networks Enhanced Logic (CAMEL) is a set of standards designed to work on either a GSM core network or the Universal Mobile Telecommunications System (UMTS) network. The framework provides tools for operators to define additional features for standard GSM services/UMTS services. The CAMEL architecture is based on the Intelligent Network (IN) standards, and uses the CAP protocol. The protocols are codified in a series of ETSI Technical Specifications.
The IP Multimedia Subsystem or IP Multimedia Core Network Subsystem (IMS) is a standardised architectural framework for delivering IP multimedia services. Historically, mobile phones have provided voice call services over a circuit-switched-style network, rather than strictly over an IP packet-switched network. Alternative methods of delivering voice (VoIP) or other multimedia services have become available on smartphones, but they have not become standardized across the industry. IMS is an architectural framework that provides such standardization.
GPRS Tunnelling Protocol (GTP) is a group of IP-based communications protocols used to carry general packet radio service (GPRS) within GSM, UMTS, LTE and 5G NR radio networks. In 3GPP architectures, GTP and Proxy Mobile IPv6 based interfaces are specified on various interface points.
The Mobile Application Part (MAP) is an SS7 protocol that provides an application layer for the various nodes in GSM and UMTS mobile core networks and GPRS core networks to communicate with each other in order to provide services to users. The Mobile Application Part is the application-layer protocol used to access the Home Location Register, Visitor Location Register, Mobile Switching Center, Equipment Identity Register, Authentication Centre, Short message service center and Serving GPRS Support Node (SGSN).
The CAMEL Application Part (CAP) is a signalling protocol used in the Intelligent Network (IN) architecture. CAP is a Remote Operations Service Element (ROSE) user protocol, and as such is layered on top of the Transaction Capabilities Application Part (TCAP) of the SS#7 protocol suite. CAP is based on a subset of the ETSI Core and allows for the implementation of carrier-grade, value added services such as unified messaging, prepaid, fraud control and Freephone in both the GSM voice and GPRS data networks. CAMEL is a means of adding intelligent applications to mobile networks. It builds upon established practices in the fixed line telephony business that are generally classed under the heading of or INAP CS-2 protocol.
Generic Access Network (GAN) is a protocol that extends mobile voice, data and multimedia applications over IP networks. Unlicensed Mobile Access (UMA) is the commercial name used by mobile carriers for external IP access into their core networks. The latest generation system is named Wi-Fi calling or VoWiFi by a number of handset manufacturers, including Apple and Samsung, a move that is being mirrored by carriers like T-Mobile US and Vodafone. The service is dependent on IMS, IPsec, IWLAN and ePDG.
Unstructured Supplementary Service Data, or USSD is a communication protocol used by GSM cellular telephones to communicate with the service provider's computers. A gateway is the collection of hardware and software required to interconnect two or more disparate networks, including performing protocol conversion.
System Architecture Evolution (SAE) is the core network architecture of mobile communications protocol group 3GPP's LTE wireless communication standard.
IP exchange or (IPX) is a telecommunications interconnection model for the exchange of IP based traffic between customers of separate mobile and fixed operators as well as other types of service provider, via IP based Network-to-Network Interface. IPX is developed by the GSM Association.