Description
The Gateway MSC in HPLMNC (GMSCC) is a specific designation for a Gateway MSC that resides within the country code portion of a subscriber's Home Public Land Mobile Network (HPLMN). The HPLMNC is the country code part of the Mobile Country Code (MCC) and Mobile Network Code (MNC) that uniquely identifies a subscriber's home network. The GMSCC is therefore the GMSCB that is physically and logically situated in the same country as the subscriber's home network operator. Its primary function aligns with the standard GMSCB: to receive incoming calls for subscribers of its network and interrogate the HLR to obtain routing instructions.
Operationally, when an international call is placed to a mobile subscriber, it is typically routed to a gateway in the destination country. The GMSCC is the node in that destination country (the HPLMNC) that receives this international call leg. It performs the HLR interrogation to determine if the subscriber is domestically located or roaming abroad. If the subscriber is domestically located, the GMSCC routes the call to the appropriate VMSC within the country. If the subscriber is roaming internationally, the HLR will provide an MSRN that points to a network in a foreign country, and the GMSCC will then route the call internationally to that visited network's VMSC.
This concept is particularly important for billing, routing efficiency, and regulatory compliance. By anchoring the call in the home country's GMSC, the home network operator maintains control over the call setup, can apply home-network specific services and policies, and ensures that call detail records (CDRs) for billing are generated at the correct jurisdictional point. The GMSCC interfaces with international gateways, the domestic SS7 signaling network for HLR access, and potentially with IP networks in later releases.
Purpose & Motivation
The GMSCC concept addresses the complexities of international call routing and regulatory requirements in global mobile communications. It defines a clear architectural point within the subscriber's home country where incoming international calls are handed over from the international carrier to the home mobile network operator. This is crucial for establishing jurisdiction for billing, lawful interception, and applying national telecommunications regulations.
Without a defined GMSCC, international calls could potentially be routed directly to a visited network when a subscriber is roaming, bypassing the home network operator. This would deprive the home operator of revenue and control. The GMSCC ensures that all calls destined for a subscriber's MSISDN first touch the home network's infrastructure in the home country, allowing for service control, fraud detection, and consistent billing practices regardless of the subscriber's location. It is a key concept in the 3GPP specifications for CAMEL (Customized Applications for Mobile network Enhanced Logic) and other intelligent network services, where the trigger for home-controlled services often occurs at the GMSCC.
Key Features
- Located within the country code of the subscriber's home network (HPLMNC)
- Serves as the first point of contact in the home country for international incoming calls
- Executes HLR interrogation to determine subscriber location (domestic or international roam)
- Anchors call control and service logic for the home network operator
- Generates billing records (CDRs) within the home regulatory jurisdiction
- Interfaces with International Switching Centers (ISCs) and the domestic signaling network
Evolution Across Releases
Introduced alongside GMSCB, with a specific focus on its role in the context of the Home PLMN Country code. Defined in the context of CAMEL and other network services that rely on the call being handled by a GMSC in the home country. Established its function for routing and service triggering for calls to roaming subscribers.
Defining Specifications
| Specification | Title |
|---|---|
| TS 23.079 | 3GPP TS 23.079 |