CAMEL/Diameter and SIP/Diameter Gateways
The N-Squared N2 Diameter/Signalling Gateway (N2DSG) is a protocol conversion appliance implementing simple integration between a Diameter-capable Online Charging Server (such as N2OCS) with standard Legacy and Next Generation protocols for in-Network Voice Call charging and control.
The Diameter/Signalling Gateway can be deployed in one (or both) of the following modes:
- N2DSG-SIP - SIP INVITE ⇄ Diameter Credit Control
- N2DSG-SCP - CAMEL/INAP InitialDP ⇄ Diameter Credit Control
Note that the Diameter/Signalling Gateway does not include any local subscriber database. Per-subscriber information is obtained at call-time via one or more of the following sources:
- From the OCS embedded within the Initial Credit-Control-Answer, or
- From the OCS or another server via a separate, dedicated Diameter request, or
- Via REST/SOAP/External-DB via client callout (supplementary feature).
User & Technical Guide
- N2SCP Technical Guide (HTML Online) [DSG Service]
- N2SVCD Technical Guide (HTML Online) [Run-Time Components]
Protocol Conformance Statements
- N2DSG Diameter Conformance (PDF Download)
- N2SCP CAMEL/INAP Conformance (PDF Download)
- N2SVCD SIGTRAN-TCAP Conformance (PDF Download)
In its simplest form, the Diameter/Signalling Gateway performs only basic call-control mapping between the network-side protocol (SIP or CAMEL) into Diameter.
However, the N2DSG also provides a script-based service development framework and helper libraries for implementing supplementary features. Typical supplementary features which would be scripted for a deployment may include:
- Pre-Call and/or Post-Call Announcements (e.g. Balance Information)
- Additional Service Logic & Configuration
- REST Client requests
- SOAP CLient requests
- Database Lookup/Update requests
The DSG logic may read information from a local or remote database. Note that the default DSG deployment does not include a database – any database creation or data management is a site-specific extension.
The SIP/Diameter call-flows are well-defined by the relevant standards:
For simplicity, the following support N2DSG-SIP features are not shown on the flows:
- Provisional ACK (PRACK)
- 401 Digest Authentication
Note that performing pre-call/post-call announcements using SIP require the N-Squared Media Server component also to be installed and configured.
For CAMEL/INAP calling, the base message flows are:
Pre-call/post-call announcements using CAMEL/INAP require the presence of an INAP-capable Intelligent Peripheral such as the N-Squared Specialized Resource Platform (N2SRP).
The N-Squared Diameter/Signalling Gateway is appropriate for small/medium-sized operators needing a simple, cost-effective gateway function for Voice/Diameter interworking.
The solution is laterally scalable with N+1 deployment for High-Availability, Geographic Redundancy, and to support increased traffic growth.
The N2DSG service definition is performed using a high-level text-based scripting language. A Graphical Interface is provided for platform maintenance. Standard Operational functions include Alarms, Statistics, and Event Data Records.
The N2DSG is built on the N2SVCD framework. The following diagram shows the N2SVCD components which are deployed for N2DSG: