Faster time to market, reduced testing, simplified management, offloading of inter-carrier agreement complexities, simplification of settlements, and lower roaming costs all help drive the perceived value of IPX Providers. In the highly specialized area of LTE roaming, IPX Provider specialists absorb complexity and reduce the cost for the Mobile Network Operators.


Interworking – Mobile Network Operators will typically interconnect with other MNOs via IPX Providers – placing responsibility for successful interworking on the IPX Provider. IPX providers face a series of challenges in support of LTE Roaming. In addition to the basic interconnect specified in IR.88, in which the IPX Providers provide mediated access to S6a, S6d, S9, and Gy interfaces via an Edge Agent, the IPX Provider must ensure security, SLA enforcement, and provide appropriate charging information for settlement.

Routing – MNOs will require a variety of routing capabilities at the network boundary to fulfill differences in applications and relationships with other MNOs. Included in these requirements are realm-based routing, IMSI-based routing, and routing based upon the content of one or more AVPs in a message.

Interoperability – Mobile Network Operators typically deploy different equipment, with different interpretations of the standards, and at different implementation and standards levels. One of the major benefits that an IPX Provider brings to a MNO is offloading of responsibility for ensuring interoperability between network operators. This can have a major positive impact on the cost of deploying roaming for the MNO.

Security – As the Network Operators interconnect their networks, each network must be protected from the other from both a malicious and an accidental damage perspective. Further, both must be protected from outside attacks. Use of encryption becomes an essential first barrier. Content-based monitoring and restriction mechanisms become an essential second level barrier – in order to prevent unauthorized service and data access and to enforce service level agreements between MNOs.

Overload Management – An important aspect of the IPX Provider’s capability is the need to manage congestion and overload in a way that preserves operation of the IPX Provider’s network and prevents client mobile network operators from overloading the hub either accidentally or intentionally. The IPX Provider must also be able to limit Signaling Storms, should they occur, preventing their propagation.

Service Level Agreement Support – Network operators deploy roaming under conditions of service level agreements (SLA). Management of the complexities and enforcement of the details of these agreements is another value add for the IPX Provider. These agreements will have features, such as total traffic throughput limitations and charging requirements that will require direct support in the IPX Provider network.

The DSC Solution

Mitel's Diameter Signaling Controller provides routing and interworking capability that meets and exceeds the basic functionality specified in the IR.88 standard, and addresses the challenges of operation in support of both Mobile Network Operators and IPX Providers.

Interworking – Acting as an IPX Hub or a DEA, Mitel's DSC provides compliance to requirements specified in IR.88. Legacy system interworking for IR.88 is addressed in the 2G-3G-4G Interworking Use Case and by the D7G product.

Routing – Using Mitel's Service-Oriented Routing™ technology, IPX Hub routing on the content of one or more AVPs, including IMSI, is supported in addition to basic functions like realm-based routing. The Ulticom DSC greatly simplifies the IPX Provider’s ongoing management of the network by minimizing necessary reconfiguration of clients as routing configurations change. Further, automatic load balancing is supplied through this mechanism, promoting the continued operation of the IPX provider network in the face of reconfigurations or outages.

Interoperability – The DSC provides a scripting mechanism that can compensate for differences in interpretation of standards and standard levels in real-time. This mechanism can examine and modify any part of a message to compensate for differences as needed. Scripting can be performed in the DEA or in the IPX Hub, depending upon need.

Security – The Ulticom DSC provides IPSEC and TLS encryption support, providing the first layer of defense for malicious attacks. The DSC also provides for White-List and Black-List security controls – enabling MNOs to control who can access their network and limiting access to only those devices that are preauthorized. This enables control of who talks to whom. And, scripting can be used to examine message content in real time if there is reason to believe that something accidental or malicious is going on.

Overload and Congestion Management – The DSC provides configurable congestion detection and action rules for both the DEA and IPX Hub and also for the external network elements, enabling reliable operation in the face of congestion and overload and providing for the preservation of the most important traffic when traffic levels exceed normal operational levels and must be damped.

SLA Support – The DSC provides features to enable SLA enforcement. In addition to security features, and ad hoc enforcement via scripting, the DSC provides for transaction rate limits on total traffic throughput on each connection and provides for CDR data collection in support of settlement for roaming activities.