An SS7 probe is a physical device to obtain signalling and/or bearer information from a

telecommunications network A telecommunications network is a group of Node (networking), nodes interconnected by telecommunications links that are used to exchange messages between the nodes. The links may use a variety of technologies based on the methodologies of circuit ...

, such as the

PSTN The public switched telephone network (PSTN) is the aggregate of the world's telephone networks that are operated by national, regional, or local telephony operators. It provides infrastructure and services for public telephony. The PSTN consists ...

or a corporate telephone system. The probe passively monitors the E1/ T1 or SDH/

SONET Synchronous Optical Networking (SONET) and Synchronous Digital Hierarchy (SDH) are standardized protocols that transfer multiple digital bit streams synchronously over optical fiber using lasers or highly coherent light from light-emitting diodes ...

bearer channels, and extracts the signalling information for onward presentation to an application. A passive probe does not affect the network under observation—this is achieved through use of protected monitor points on the network

distribution frame In telecommunications, a distribution frame is a passive device which terminates cables, allowing arbitrary interconnections to be made. For example, the Main Distribution Frame (MDF) located at a telephone exchange, telephone central office te ...

Applications

The network application may be lawful interception or a revenue-generating application such as

missed call A missed call is a telephone call that is deliberately terminated by the caller before being answered by its intended recipient, in order to communicate a pre-agreed message. It is a form of One-bit message, one-bit messaging. Missed calls wer ...

. Probes are also extensively used in operational support systems (OSS). Applications served by probes include solutions for inter-carrier billing, revenue loss (by-pass/ phantom traffic and analysis services), fraud prevention, billing, local number portability, quality of service, surveillance ( global call trace), maintenance (

protocol analysis Protocol analysis is a psychological research method that elicits verbal reports from research participants. Protocol analysis is used to study thinking in cognitive psychology (Crutcher, 1994), cognitive science (Simon & Kaplan, 1989), and behavio ...

), traffic engineering (link and trunk forecasting), alarming and SS7, Sigtran and IS-41 monitoring. Passive monitoring probes provide a network and switch vendor-independent solution for network applications.

Lawful interception

Lawful interception concerns the delivery of calls and data to government approved reception centres. Interception is authorized through a legal framework, such as UK RIPA or US CALEA{{cite web , url = http://www.askcalea.net/calea/ , title = CALEA , access-date = 2008-07-28 , author = US Government , date = 2008-07-28 , url-status = dead , archive-url = https://web.archive.org/web/20080914172940/http://www.askcalea.net/calea/ , archive-date = 2008-09-14 or Russia SORM.

Technology

SS7 probe technology provides the correct physical interface to the telecommunications network. Opportunities for probing occur in both traditional TDM infrastructure as well as in ATM and IP networks. The different characteristics and infrastructure used for these interfaces is reflected in the types of interfaces to be monitored. These range from E1 or T1 2 Mbit/s or 1.5Mbs to SDH and

STM-x OC-x multiplexes.

Notes

Privacy of telecommunications Telephony signals Electronic test equipment