Network switching subsystem (NSS) (or GSM core network) is the component of a GSM system that carries out call switching and mobility management functions for mobile phones roaming on the network of base stations.

The NSS originally consisted of the circuit-switched core network, used for traditional GSM services such as voice calls, SMS, and circuit switched data calls. It was extended with overlay architecture to provide packet-switched data services known as the GPRS core network. This allows mobile phones to have access to services such as WAP, MMS, and the Internet.

Areas of activity
  • Signaling Transfer Point (STP) – The STP is a router that relays SS7 messages between signaling end-points (SEPs) and other signaling transfer points (STPs). HP OpenCall IP-STG is a server-based commercial, off-the-shelf Signaling Gateway, running on standard OS (Linux). It provides ability to bridge the IP SIGTRAN network and SS7 network, translates signaling information exchanged by the services on both sides, manages network and protocol complexity, rich feature set such as intelligent routing capabilities, provides the physical termination of the SS7 links, routing of SS7 and IP messages, and network management of SS7 and IP nodes.
  • Home Location Register (HLR)/ Authentication Center (AuC) – The HLR is a database used for storage and management of subscriptions. The HLR is considered the most important database, as it stores permanent data about subscribers, including a subscriber’s service profile, location information, and activity status. The Authentication Center is a protected database that stores a copy of the secret key stored in each subscriber’s SIM card, which is used for authentication and ciphering of the radio channel. HP OpenCall HLR/AuC is a proven World-class HLR solution that features industry-leading performance and reliability. The HP OpenCall HLR/AuC is implemented as One Logical HLR Database across multiple physical platforms deployed in different physical locations such that geographic redundancy is obtained. From a network and provisioning viewpoint, the Single Logical HLR database has many benefits in terms of provisioning and network routing which will be dramatically simplified, as there won’t longer be any requirement for deterministic access of subscriber data: All subscribers will be inside one database with 100% data integrity under all circumstances.
  • Equipment Identity Register (EIR) – The EIR is a database that contains a list of all valid mobile equipment on the network, where its International Mobile Equipment Identity (IMEI) identifies each MS. An IMEI is marked as invalid if it has been reported stolen or is not type approved. The EIR functionality is implemented by HP OpenCall EIR which is co-located with HP OpenCall HLR solution. HP OpenCall EIR also implements the function ADD (Automatic Device Detection), which allows real-time tracking of change phone number, and send appropriate notification to the platform DMS. Device Management solution for EIR can maintain white/black/grey lists of IMEIs as well as various other functions like: load/extract of data in different formats, automatic events notification, extended CheckIMEI message support, clone IMEIs detection etc.
  • Home Subscriber Server (HSS) – The HSS is a database used for storage and management of subscriptions in IMS/EPS networks. It replaces HLR/AuC/EIR functionality which was applied to GSM networks. HP OpenCall HSS provides functionalities per latest 3GPP standards.

In addition to NSS components Delta Solutions provides SMS Anti-SPAM system which allows operators to control SMS and avoid various SMS related attacks like spam, fishing, spoofing etc.