The Signaling System Number Seven (SS7) is a suite of protocols that were standardized in the 1980s in ITU-T Q.700 series. New protocols added in the 1990s and 2000s by ETSI and 3GPP to support mobile phones and the services they need (roaming, SMS, data…)
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 mobile phone 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 MAP protocol is responsible for providing the following functionality:
Mobility Management, Operation and Maintenance, Call Handling, Supplementary Services and Short Message Service (Dryburgh, Hewet, 2005)
The Customized Applications for Mobile network Enhanced Logic (CAMEL) was introduced to allow mobile operators to build custom services that were not possible through MAP. The CAMEL Application Part (CAP) along with the Mobile Application Part (MAP) is going to be the focus of this paper.
SS7 was traditionally served over Time Division Multiplexing (TDM) networks; however with the increasing use of IP networks, SIGTRAN (Derived from Signal Transfer) was introduced as part of the SS7 protocol family but uses an IP protocol called Stream Control Transmission Protocol (SCTP) as the transport layer for SS7 (IETF, 1999).
What is SS7?
Signaling System 7 (SS7) is a set of protocols used to control and manage the signaling network in telecommunications. It was developed in the 1970s and has since become the standard for signaling in fixed and mobile networks worldwide. SS7 enables the exchange of information necessary for call setup, routing, and other network services.
How Does SS7 Software Work?
SS7 software operates on a separate network from the voice and data traffic, ensuring efficient and reliable signaling communication. It uses a packet-switched network to transmit signaling messages between various network elements, such as switches, routers, and databases.
The SS7 protocol stack consists of different layers, each serving a specific function:
- Physical Layer: Handles the transmission of signaling messages over physical media, such as copper or fiber-optic cables.
- Data Link Layer: Provides error detection and correction mechanisms for reliable data transmission.
- Network Layer: Handles the routing of signaling messages between different network elements.
- Transport Layer: Ensures the reliable delivery of signaling messages between network elements.
- Application Layer: Implements the specific services and functions required for call setup, routing, and other network services.
Functions of SS7 Software
SS7 software performs a wide range of functions that are essential for the smooth operation of telecommunication networks. Some of the key functions include:
- Call Setup: SS7 enables the establishment of voice and data calls by exchanging signaling messages between network elements.
- Number Portability: SS7 allows users to retain their phone numbers when switching service providers.
- Short Message Service (SMS): SS7 supports the exchange of text messages between mobile devices.
- Location-Based Services: SS7 enables the provision of location information for emergency services and value-added services.
- Roaming: SS7 facilitates the seamless handover of calls and data sessions between different networks, ensuring uninterrupted service for mobile subscribers.
- Intelligent Network Services: SS7 enables the implementation of advanced network services, such as call forwarding, call waiting, and prepaid billing.
SS7 software plays a crucial role in the functioning of telecommunication networks, enabling efficient and reliable signaling communication. Its various functions, such as call setup, number portability, and location-based services, contribute to the seamless operation of voice and data services.