Home Subscriber Server(HSS)/Home Location Register(HLR) and Unified data management (UDM)

In the telecom core network, a subscriber profile is stored at a node in the subscriber’s home network. Its name changes with the type of mobile generation, e.g., 3G (HLR), LTE (HSS), and 5G (UDM).

ComCode provides a unified solution for all generations, known as the Home Subscriber Server (HSS), that supports all services (e.g., voice, data, SMS, etc.) across all generations (3G, LTE, 5G).

Who can use HSS?

A company that provides mobile service using SIM cards can use ComCode’s HSS solution to support 3G, LTE and 5G services. For example, an MVNO, MNO, or a Private LTE network provider can use our software solution.

Support for 3G over High Performance SS7/Sigtran stack.

SS7 is the protocol that is used by the 3G network, and the HSS supports the SS7/Sigtran, to support GSM MAP operations for roaming, data, and messaging. The ComCode HSS solution supports the following:

Authentication
Voice
GPRS
Location Retrieval.
MSRN lookup APIs.
Camel CSIs for MO, MT, SMS, etc.
Operator Determined Barring
Subscriber Control Supplementary Services.
Call Forwarding.
Call Waiting.
CLOP, CLIP, CLIR, etc.

Support for LTE over Diameter Protocol.

The LTE is a diameter protocol based network for roaming. It used 3GPP S6a/S6d interfaces to enable a mobile device to Authenticate and Attach to a LTE network via MME. The HSS supports the following features.

4G Authentication.
Subscriber Attach,
Subscribe Notify,
SMS Enable in HSS over NAS using Diameter.
Operator Determined Barring.
Purge

Support for 5G SA and NSA over Diameter and HTTPv2.

5G is the next-generation network known as NR (New Radio). It is based on a service-based architecture that uses the HTTP/2 protocol. The HSS has an inbuilt UDM that supports Nudm and other interfaces.

With 5G SA, all communication is over HTTPv2, where the HSS subscribes to the NRF. If any service, such as AMF, needs to communicate with UDM, it performs the lookup using NRF and sends signaling messages to the HSS/UDM.

With 5G NSA, No HTTPv2 involved, the Non-Stand-Alone, 5G uses NR Radio with EPC Core (LTE). When HSS knows that a device is using 5G NSA, it includes NR as a secondary RAT in the Update Location Request. HSS supports extended bit-rate values to support 5G NSA.

Support for IMS using Diameter-based Cx/Sh interfaces.

LTE and 5G are data-only networks. To support sms, voice, and video calls, the network relies on Internet Multimedia Services (IMS). IMS is a standardization of multimedia services for packet networks that uses the SIP and RTP protocols to exchange Signaling and Media. The ComCode’s HSS supports Cx and Sh interfaces for IMS. Where a device can attach, authenticate, make calls, SMS, etc., using Diameter-based Cx/Sh.

Support for Auc (3G/LTE) and AuSF(5N) in HSS/UDM:

AuC stands for Authentication Center. It is a Node in the mobile core network that stores subscribers’ authentication keys and generates authentication vectors. The vectors are generated based on the sequence number. The ComCodes HSS solution includes an authentication center for 3G, 4G, and 5G, along with ReSynch support for sequence numbers. It supports the following key types.

Plain Ki and OPC
EKi and OP with K4
EKi and OPC
SUPI for 5G
SUCI for 5G with type 1 and 2.
IMS Authentication.

Large volume support for subscribers using a scalable approach.

The HSS uses the concepts of instances and functional decoupling. It uses MongoDB for storing a large number of subscribers.

The HSS supports redundancy as follows.

Multiple Diameter Stack instances can be deployed; each instance can connect to any HSS/UDM/HLR instance.
Multiple HSS/UDM/HLR instances, any one can process a subscriber transaction.
DB cluster.
Redundant Provisioning Servers.
Centralized CDRs

Customer APIs for Subscriber profile Management.

The HSS solution comes with a rich set of customer APIs. Using APIs, a telecom service provider can control subscriber profiles for 3G, 4G, 5G, and IMS, along with external system integration for roaming checks and subscriber de-attach.

Support for the SIP interface to terminate an MT call.

In the world of IP telephony, the call is over an IP network using the softswitches. For a terminating call, the soft switch needs to know the address of the serving MSC. For that, it sends an invite to the HSS. Where HSS queries the network over SS7 to get the roaming number. HSS returns the roaming number to the softswitch.

HSS and IP Short Message Gateway (IP-SM-GW)

An IP SM Gateway is a node in the telecom network that bridges the Legacy SS7 and IMS network for Short Message delivery. A mobile service provider that has an existing SMSC for 3G, but has also enabled devices to send/receive SMS over an IP network, requires IP-SM-GW.

How ComCode’s HSS supports SMS over IP.

The HSS supports operations to register a subscriber for messaging over the IMS network via IP-SM-GW.
De-Registration of a subscriber for messaging over a data-only network.
Interactions with SMSC for subscriber lookup.
HSS returns the IP-SM-GW address if the subscriber is on IMS, otherwise, the MSC address.

From Subscriptions to Satisfaction

The success of your LTE network depends on how well the HSS performs. With our expertise in telecom architecture and innovative deployment strategies, we help you build networks that are fast, protected, and future-proof. Our solutions are designed to evolve with your business, not limit it.