> For the complete documentation index, see [llms.txt](https://gsm.learn-telecom.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gsm.learn-telecom.com/architecture/nss-network-switching-subsystem.md).

# NSS - Network Switching Subsystem

#### Network Switching Subsystem (NSS)

The Network Switching Subsystem (NSS) is a key component in a GSM network responsible for call processing and subscriber mobility management. It consists of several network elements, including:

* **Mobile Switching Center (MSC):** Manages call setup, routing, and mobility.
* **Home Location Register (HLR):** A database storing details of each subscriber.
* **Visitor Location Register (VLR):** Temporarily holds data about subscribers currently in the MSC area.
* **Authentication Center (AUC):** Provides data for verifying user identity.
* **Equipment Identity Register (EIR):** Keeps records of mobile equipment to prevent fraud.

The NSS facilitates communication between mobile users and connects them to other networks.