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Flexible, scalable and cost-effective solutions providing seamless roaming between legacy 2G/3G networks and today’s 4G LTE networks.

The facts

LTE networks have been launched by 729 operators in 221 countries reaching 83% of the population (as of May 2019)

GSMA is predicting an increase of a third by the end of 2020.

Lte networks infographic

The challenge

As with all new technology you cannot simply deploy it in a vacuum disregarding what’s gone before in the way of legacy technology. How do operators navigate the mix of networks to successfully provide roaming services to their subscribers, whilst cost-effectively taking advantage of lucrative roaming revenues from inbound roamers?

For those deploying 4G networks, or existing 3G networks looking to offer 4G roaming agreements, they need to sort out 3G < > 4G roaming interoperability, otherwise…

  • Operators will fail to retain subscribers if the moment they step out of their home networks their service no longer works.

  • Operators will lose revenue if they’re unable to successfully charge prepaid subscribers dynamically credit-checked over legacy protocols.

  • Operators will lose subscribers unless they can seamlessly roll out new services that work as they roam outside of their home network.
no signal man

At the heart of the problem

At the heart of the problem is that 2G/3G networks are built upon legacy SS7 protocol technology, whereas 4G LTE networks are developed around the Diameter protocol.

What is required is a bridge between these technologies, one that will seamlessly allow the sharing of policy, charging and authentication information.

roaming globe

The solution

The industry has developed a set of standard DIAMETER signalling-based network products. Included in this product set is the Interworking Function (IWF), a sub-component of the Diameter Signalling Controller (DSC) that provides 3GPP specified DIAMETER to SS7 CAMEL, MAP interworking.

3G4GLTE bridge

Case Study

Integrating an OCS platform to facilitate 4G < > roaming

Having begun work to deploy an IWF with a 4G operator in Europe, whose network is built by one of the big vendors and makes use of a state-of-the-art OCS (Online Charging System) from a specialist vendor, (incidentally the OCS doesn’t support Camel it only supports Diameter), it became apparent that supporting prepaid subscribers was not straight forward. It transpired that in the 3G network credit checks were sent to handsets over USSD (Unstructured Supplementary Service Data).

ussd iwf blue
tas iwf blue

Our IWF product is tightly integrated with our Telephony Application Server (SVI-TAS) that provides a set of flexible APIs to allow for the rapid deployment of new interfaces, in this instance used to provide a USSD to DIAMETER Gateway. The affinity between our DSC and TAS provides a huge degree of flexibility to clients, enabling them to rapidly test and deploy new services and ensure full interoperability between vendors and network devices, resulting in a future-proof solution.

The operator then went one step further and delivered a separate USSD application, deciding the interface to the OCS would optimally be performed over HTTP. Read the full case study here and learn more find out about the redundancy, load sharing, routing, session binding and NFV compatibility of the solution >>>

Further Information

3g-4g roaming presentation graphic

Read our latest whitepaper on solving the 4G LTE mobile roaming puzzle 

svi gmsc icon

Find out more about our
SVI-GMSC Gateway MSC product

svi iwf icon

Find out more about our
SVI-IWF Interworking Function