Editing Network switching subsystem (section)

==Equipment identity register (EIR)==
'''EIR''' is a system that handles real-time requests to check the [[International Mobile Equipment Identity|IMEI]] (checkIMEI) of mobile devices that come from the switching equipment (MSC, [[SGSN]], [[Mobility Management Entity|MME]]). The answer contains the result of the check:

* whitelisted – the device is allowed to register on the network.
* blacklisted – the device is prohibited from registering on the network.
* greylisted – the device is allowed to register on the network temporarily.
* An error ‘unknown equipment’ may also be returned.

The switching equipment must use the EIR response to determine whether or not to allow the device to register or re-register on the network. Since the response of switching equipment to ‘greylisted’ and ‘unknown equipment’ responses is not clearly described in the standard, they are most often not used.

Most often, EIR uses the IMEI blacklist feature, which contains the IMEI of the devices that need to be banned from the network. As a rule, these are stolen or lost devices. Mobile operators rarely use EIR capabilities to block devices on their own. Usually blocking begins when there is a law in the country, which obliges all cellular operators of the country to do so. Therefore, in the delivery of the basic components of the network switching subsystem (core network) is often already present EIR with basic functionality, which includes a ‘whitelisted’ response to all CheckIMEI and the ability to fill IMEI blacklist, which will be given a ‘blacklisted’ response. 

When the legislative framework for blocking registration of devices in cellular networks appears in the country, the telecommunications regulator usually has a Central EIR ([[Central Equipment Identity Register|CEIR]]) system, which is integrated with the EIR of all operators and transmits to them the actual lists of identifiers that must be used when processing CheckIMEI requests. In doing so, there may be many new requirements for EIR systems that are not present in the legacy EIR:

* Synchronizing lists with CEIR. CEIR systems are not described by a standard, so the protocols and exchange mode may differ from country to country.
* Supporting additional lists – IMEI white list, IMEI grey list, list of allocated [[Type Allocation Code|TACs]], etc.
* Support in lists not only IMEI but also bindings – IMEI-IMSI, IMEI-MSISDN, IMEI-[[International mobile subscriber identity|IMSI]]-[[MSISDN]].
* Supporting the customized logic of lists applying. 
* Automatic adding the item to a list in separate scenarios.
* Sending [[SMS]] notifications to subscribers in separate scenarios.
* Integration with the billing system to receive IMSI-MSISDN bundles.
* Accumulating the subscribers’ profiles (history of device changing).
* Long-term storage of processing of all CheckIMEI requests.

Other functions may be required in individual cases. For example, Kazakhstan has introduced mandatory registration of devices and their binding to subscribers. But when a subscriber appears in the network with a new device, the network operation is not blocked completely, and the subscriber is allowed to register the device. To do this, there are blocked all services, except the following: calls to a specific service number, sending SMS to a specific service number, and all Internet traffic is redirected to a specific landing page. This is achieved by the fact that EIR can send commands to several MNO systems (HLR, [[Policy and charging rules function|PCRF]], [[Short Message service center|SMSC]], etc.).

The most common suppliers of individual EIR systems (not as part of a complex solution) are the companies BroadForward, Mahindra Comviva, Mavenir, Nokia, Eastwind.