The Authentication Gateway (AGW) acts as HTTP Proxy for other services, providing authentication using the HSS and SIM-Card credentials. Typical use cases are the Ut-Interface for supplementary service configuration or other custom web-based services. It supports Header insertion, URL rewriting as well as load sharing and failover capabilities.

The PCRF dynamically allocates and manages bandwidth requirements for various use cases. For VolTE/VoNR, it is required to provide a better QoS to provide an excellent user experience. The PCRF provides the QoS authorization that decides how a certain data flow will be treated in the PCRF, typically the PGW, and ensures that this follows the user’s subscription profile.

Main Features of ng-voice’s PCRF:

• Support of Diameter Gx interface with PGW/GGSN as per 3GPP TS 29.210
• Support of Diameter Rx interface with CSCF as per 3GPP TS 29.214
• Support Dynamic PCC rules
• Support both session and bearer binding as per 23.203 during ims default and dedicated bearer setup and teardown
• Provide QoS information
• Support network initiated dedicated bearer establishment based on application (e.g. the P-CSCF) request over the Rx interface.
• Support Network Provided Location Information during IMS call initiation

The PCRF is compliant to 3GPP release 15. Applicable standards include 3GPP TS 29.212, TS 23.203, TS 29.213 and TS 29.214.

ng-voice provides a software solution for the Home Subscriber Server (HSS), Home Location Register (HLR), Authentication Centre (AuC), and Equipment Identity Register (EIR) functionalities. ng-voice’s subscriber database solution supports 3G, 4G, and 5G technologies and VoLTE, VoNR, and VoWiFi services.

The HSS is the System Architecture Evolution (SAE) ‘s central database in LTE networks where important subscriber information is stored. GSM networks have a Home Location Register (HLR) and Authentication Centre (AuC). The equivalent of this in LTE networks is the HSS. The MME/SGSN interfaces the HSS over the S6a/S6d Diameter interface for authentication, location, and service information about the subscriber.

Besides LTE, the HSS is also a functional element of IMS/VoLTE. The HSS database supports the IMS network entities that handle calls/sessions. It contains user profiles, performs authentication and authorization of the user, and can provide location information of the user. From an IMS perspective, the components communicating with the HSS are the Application Servers (AS) and Call State Control Function servers (CSCFs). On being queried by the Interrogating-CSCF (I-CSCF) when SIP registration is performed, the HSS retrieves the Serving-CSCF (S-CSCF) address and assigns it to a user. The user’s information and profile data are then downloaded from the backend database and stored by the HSS, where the data can be accessed. After successful authentication on the same interface, the S-CSCF downloads the subscriber’s profile over the Cx Diameter interface. The profile contains the Initial Filter Criteria providing the logic to the IMS for triggering SIP messages to the appropriate Application Servers. Application Servers (AS) access the HSS over the Sh diameter interface. Besides public identifiers, IMS user identities, and location information, the HSS also stores repository data related to a service (e.g., supplementary service data).

Furthermore, the Authentication, Authorization, and Accounting (AAA) function interfaces the HSS over the SWx interface to support non-3GPP access to the network for VoWiFi service.

ng-voice’s subscriber database solution also provides Authentication Centre (AuC) and Equipment Identity Register (EIR) functionalities. The AuC provides authentication parameters (e.g., authentication vectors) for the authentication process. The EIR provides blacklisting/whitelisting functionalities over the S13 interface.

ng-voice’s subscriber database solution has a comprehensive feature set. The feature set is listed below.

Main Features of ng-voice’s Subscriber Database Solution:

• Supported interfaces include:
  • S6a and S6d interfaces provide procedures for attaching the device to 3G and 4G packet networks.
  • Cx and Sh interfaces provide procedures for accessing IMS services.
  • SWx interface providing procedures for VoWiFi access.
  • Zh interface provides authentication procedures for Supplementary Service configuration.
  • The S6c interface provides procedures for SMS operations with the HSS.
    5G interfaces including Nhss, NU1, NU2, N70 and N71.
  • SS7 MAP interfaces, including MAP C and MAP D, through an additional interworking function, translating S6d to MAP
• Authentication procedures included EPS AKA, IMS AKA, and 5G AKA.
• Provisioning through REST-based APIs.
• User Management through GUI
• Robust and geo-redundant backend database

The HSS is compliant to 3GPP release 17. Applicable standards include 3GPP TS 29.228, 3GPP TS 29.229, TS 24.229, TS 29.328 and TS 29.329.

The ng-voice IP-SM-GW provides SMS interworking between native VoLTE handsets and other networks using a standard MAP protocol.

While the SIP protocol is one of the most popular protocols used for voice calls, SS7/MAP (Mobile Application Part) is a widely used protocol for SMS service. MAP is used between the SMSC and IP-SM-GW to allow MO-SM origination and MT-SM delivery over the IMS. CS terminating SMS is also delivered via the SMSC and signaling passes the IP-SM-GW if the SMS originates on IMS.

The solution supports S6c diameter interface towards HSS to enable the retrieval of routing information for the transfer of short messages and to report the status of the delivery status of a short message. Together with its “Store and forward” capabilities, it eliminates the requirement for a standalone SMSc in pure 4G/5G networks.

The IP-SM-GW is compliant to 3GPP release 15.

The MMTel enhances the telephony service with the following features:

• Call Forwarding (unconditional, busy, not available, timeout)
• Call Forward Targets (to number or voice box)
• Call Blocking (inbound, outbound, anonymous call rejection, black-lists, white-lists, matching patterns)
• CLIP/CLIR
• Dialing patterns
• Network announcements through MRF
• Full feature-set in alignment with GSMA IR.92

Besides talking to the IMS Core and or MRF using the standardized ISc interface, it provides the following external interfaces:

• Sh-Interface (Diameter) towards the HSS for storing and retrieving the settings from a centralized HSS
• Ut-Interface (XCAP) towards the User-Equipment (UE) for configuring the settings directly on the handset
• It may also integrate with the IT systems via Diameter over the Rf reference point.

The MMTel is compliant to 3GPP release 15. Applicable standards include 3GPP TS 29.328, TS 29.329, TS 24.623, TS 24.607. TS 24.604 and GSMA IR 92.

The ng-voice MRF provides media-related functions such as conferencing and announcements. The ng-voice MRF is a combined MRFC (Media Resource Function Controller) with a MRFP (Media Resource Function Processor).

The MRF is compliant to 3GPP release 15. Applicable standards include RFC 4240 and 3GPP TS 24.229.

Operators who want to offer VoWiFi to their end-users require the addition of AAA and ePDG to the Packet Core and IMS. WiFi supplements LTE coverage. Subscribers can use WiFi to access EPC networks when LTE coverage is unavailable. As there are different access networks in scope, there is a need for handover between VoLTE and VoWiFi to ensure continuity of services. Hence, the handover function is one of the features of the solution.

VoWiFi subscribers use the ePDG to attach to an EPC network and then register with the IMS network. The ePDG interworks with the AAA server to authenticate the UEs. After UE authentication, the ePDG forwards messages to the PGW over the S2b interface.

The main features of the solution are as follows:

• ePDG interworks with the AAA and PGW, providing signaling and data channels for UEs.
• The AAA interworks with the ePDG over the SWm interface to authenticate VoWiFi subscribers.
• The AAA interworks with the PGW over the S6b interface and interworks with the HSS over the SWx interface.

The ePDG/AAA is compliant to 3GPP release 15. Applicable standards include 3GPP TS 23.402, TS 33.402, TS 29.273 and TS 29.274.

The ng-voice SCC-AS with SRVCC functionality provides seamless handover from a 4G packet-switched networks towards a legacy 2G/3G circuit switched network as well as T-ADS functionality.

In case a handover is requested by the MSC of the 2G/3G network, a voice call towards the Session-Transfer Number (STN-NR) is initiated and the ng-voice SCC-AS initiates an RE-INVITE (for connected sessions) or an UPDATE (for sessions in early stage) to the other party to update the Media-Path for a session, in accordance with RFC 3891. SRVCC is implemented according to 3GPP Release 8.

Furthermore, the SCC-AS provides the T-ADS functionality to enable proper domain selection for correct call routing. In ng-voice’s T-ADS solution, calls are terminated by default to ng-voice’s IMS. An IMS registration check of the terminating user determines whether the IMS continues routing the call over IMS or routes the call back to the CS network.

The IMS Platform, as a communications platform carrying voice, fax, and messaging data has to provide means for lawful interception of the content of communication by third-party entities. Law Enforcement Agencies (LEAs) have to be able to connect to the IMS platform in a standardized way — ETSI, 3GPP, and other organizations define the interface (and data exchange) between telecommunication operators and LEAs.

ng-voice provides the X1, X2, X3 interfaces:

• X1 – The X1 interface is used by an LI provider to create, modify, delete, and list interceptions on the IMS platform
• X2 – The X2 interface is a TLV (Type–length–value) based interface with a simple request/response mechanism over a secure TLS connection, used to pass intercepted signaling data towards an LI provider.
• X3 – The X3 interface is also a TLV-based interface with a binary payload encapsulating the intercepted RTP data.

USSD is typically used to provide supplementary services, such as credit-queries and cash-up for prepaid services. It may also be used for any other service, such as interactive news retrieval or any other text-based and interactive service.

ng-voice provides a simple to use and easy to integrate USSD-Gateway which allows you to quickly build and integrate USSD-services without having the need to fallback to 2G/3G for using such services. It connects directly to the IMS-Core using a standardized ISc-Interface and can send and retrieve the user input and the responses from and to a subscriber from a web-based service.