What is MAP in SS7?

 Introduction

The mobile application part is an SS7 protocol that provides an application layer for nodes in GSM, UMTS, and GPRS networks. It establishes and manages wireless calls over the public switched telephone network.

SS7 MAP links scattered switching components known as mobile switching centers (MSCs) with a master database known as the Home Location Register (HLR). The HLR dynamically records a mobile network subscriber's current location and profile. The HLR is reviewed during the processing of an incoming call and updated as the subscriber progresses through the network and is served by several switches.

Outline

This article will discuss the SS7 protocol mobile application part(MAP). We will talk about different types of SS7 Map Phase 2 operations. We will also discuss their functions.

The following are the major types of SS7 MAP Phase 2 operations:

• Mobility Management 

• Maintenance and Operation 

• Call Handling 

• Supplementary Services 

• Short Message Service

Mobility Management: Mobility management operations are classified as follows:

• Paging and Search 

• IMEI Management 

• Access Management 

• Security Management 

• Subscriber Management 

• Identity Management 

• Location Management 

• Handover

• Authentication Management

To reduce interactions with the HLR, it solely stores location information about the MSC/VLR to which the subscriber is connected. The VLR includes more comprehensive location information, such as the real roaming region of the user. Each time a subscriber changes location area, VLR needs updated location information. If the subscriber switches VLR, the HLR's location information has to be changed.

The following are examples of location management operations:

• update location - Message used by VLR to notify HLR of changes in the VLR region.

• cancel location - HLR uses the cancelLocation function to erase a subscriber's profile from the prior VLR.

• send identification - To get authentication information, the new VLR uses a send identification operation to query the old VLR. The TMSI is sent as a parameter to the send identification procedure, and the result includes the IMSI and other authentication information (RAND, SRES, and, optionally, KC). If it cannot receive this information, it may obtain it from the HLR using the sendAuthenticationInfo method.

• purgeMS - This message is issued if an MS has been dormant over a long time (no calls or location updates). The VLR sends this message to the HLR to indicate that it has removed its data for that specific MS.

Handover: The sections that follow outline SS7 MAP handover operations:

• prepareHandover - At the commencement of an essential inter-MSC handover, the prepareHandover message is used to transport a request and answer between the two MSCs.

• sender signal - Following a successful inter-MSC handover (in the case of a basic changeover, from MSC-A to MSC-B), MSC-B sends a sender signal message to MSC-A to enable it to surrender its radio resources.

• forwardAccessSignalling 

• processAccessSignalling

prepareSubsequentHandover: If additional inter-MSC communication is necessary (either back to MSC-A or another MSC, C), MSC-B forwards this message to MSC-A. It includes the data needed for MSC-A to send a prepareHandover message to MSC-C.

Authentication Management: The single authentication management action in Phase 2 is the MAP operation sendIdentificationInfo.

IMEI Management: CheckIMEI is the single SS7 MAP operation in the IMEI management category, and it is used to determine if a piece of mobile equipment is on a black, grey, or white list. In a MAP check IMEI procedure, the MSC delivers the IMEI to the EIR. The EIR verifies the IMEI's status and reports back to the MSC.

Subscriber Management: When a subscriber's profile changes, an HLR employs subscriber management processes to update a VLR with detailed subscriber data. 

Because the operator has altered the subscription of the subscriber's basic services or one or more supplemental services, the subscriber's profile may be adjusted.

- insert subscriber data: The HLR utilizes the insert subscriber data operation to send the current subscriber profile to the VLR.

- DeleteSubscriberData: The deleteSubscriberData action is used by the HLR to notify the VLR that a service has been deleted from the subscriber profile.

- Restore data: When a VLR gets a provide roaming number request from the HLR for an IMSI that the VLR is unfamiliar with or an IMSI for which the VLR entry is unreliable due to an HLR outage, the VLR sends a restore data message to the HLR to synchronize the data.

Call Handling: There are no subcategories of operations in call handling; there are just two:

• sendRoutingInfo - Based on the MSISDN, the GMSC then determines the subscriber's HLR and calls the MAP operation to send routing information with the MSISDN as a parameter toward the HLR to determine where the MS is now situated.

• Provide roaming number - The HLR already knows the VLR that serves the subscriber due to previous location updates. 

The HLR requests the VLR using the operation provide a roaming number with the IMSI as an input to get a mobile station roaming number (MSRN). The VLR selects an MSRN from a pool of available numbers and transmits the MSRN in an acknowledgment to the HLR.

Supplementary Services: The following operations are classified as supplemental services:

• register SS - The register SS action is used to enroll subscribers in a supplemental service.

• erased - EraseSS is used to remove a supplemental service entered for a specific subscriber using register SS.

• activate SS - This function is used to activate a supplemental service for a specific subscriber.

• deactivate SS - This action disables a supplemental service for a specific subscriber.

• interrogate SS - InterogateSS queries the condition of a single supplemental service in the HLR for a specific subscriber.

• register password - This procedure establishes or modifies a password for an additional service. 

When the HLR gets this message, it sends a Get password message to obtain the old password.

• get the password - If the subscriber wishes to change his existing password or alter or activate a supplemental service, the HLR sends this message.

Unstructured Supplementary Services (USSs): USSs enable PLMN operators to develop and swiftly offer operator-specific supplementary services to the market. 

Unstructured supplementary service data (USSD) data packets are used for communication. Unlike SMS, which uses a save and forward technique, USSD is session-oriented and offers a quicker turnaround and response time than SMS, which is especially useful for interactive applications. USSD can complete the identical two-way transaction seven times faster than SMS.

SMS (Short Message Service): 

It performs the following functions:

 • reportSMDeliveryStatus • forwardSM • alertServiceCentre • informServiceCentre 

• sendRoutingInfoForSM • ready For SM

Conclusion

The mobile application component is an SS7 protocol that serves as an application layer for GSM, UMTS, and GPRS network nodes. It connects and controls wireless calls via the public switched telephone network. Secgen is helping you to get this SS7 Protocol