LTE (and thus Diameter) Interworking Moves Center Stage

Mobile Musings

LTE (and thus Diameter) Interworking Moves Center Stage

By Jim Machi, SVP of Marketing  |  May 20, 2013

As LTE (News - Alert) rollouts occur and create yet another network (an awesome and fast one) with lots of subscribers, the need for these subscribers to connect to other networks arises. At first glance, these subscribers may look like they live in a bubble, since their faces are seemingly stuck to their tablets or smartphones all the time, but they don’t actually live in a bubble. In reality, subscribers move around both physically and cyberspace-ically.  If you just want to use the network to be a mobile on-ramp to the Internet and watch YouTube (News - Alert) or get to Facebook faster, that’s fine. But all of these subscribers actually move around one way or another, and the need to connect to these other networks becomes important for revenue generation. Additionally, the carriers proactively direct smart devices to Wi-Fi so they can offload traffic from their cellular networks.

Since LTE uses Diameter as a signaling protocol, operators have a need for Diameter interworking with the signaling technologies used in other networks. This has given rise to the Diameter Interworking Gateway function, which moved onto the center stage at Mobile World Congress (News - Alert) this year. It’s a critical element to enable the successful rollout of LTE and a seamless user experience across different networks.

Let’s take a look at some of the key use cases:

1.      Legacy network interworking, namely signaling conversation from Diameter to SS7/MAP: Sub-scenarios here include roaming between LTE and 2G/3G networks, security hand-off and home location register subscriber authentication. Since LTE will only account for 10 percent of all access networks by 2017, this roaming use case will be critical for LTE-legacy network interoperability.

2.      Wi-Fi interworking: Wi-Fi interworking requires signaling conversion from RADIUS to Diameter to connect the Wi-Fi network to the carrier’s central traffic management and charging systems. This allows carriers to offer subscriptions that combine mobile and Wi-Fi connectivity into a single bundle.

3.      IT interworking: This requires connecting the new Diameter-based systems, such as a PCRF or a Diameter signaling controller, to either SOAP or XML/HTTP so IT information systems, such as CRM and subscriber databases, can be used for policy and routing decisions.

4.      LTE to IMS: On the surface, both LTE and IMS use Diameter, so why would interworking between these be required? Because, as you readers know, in the VoIP world, just because SIP is on one device doesn’t mean it talks to another SIP device automatically. Different SIP versions might be used, or the vendors might have interpreted the specs just a little differently, both of which result in poor interworking. It will be the same story for Diameter, and I understand there are close to 70 different variants of Diameter alone right now.

So, if you are a network operator, are these issues real? Well, they’re real enough that the 3GPP and GSMA (News - Alert) have identified elements called Diameter Routing Agent (DRA),  Diameter Edge Agent (DEA), and Diameter InterWorking Function (IWF), which is more closely aligned to the interworking described above. And these issues are real enough that addressing them took up a good portion of my Mobile World Congress week. And they’re real enough that Infonetics (News - Alert) identifies the Diameter signaling controller market in a recent report with an almost 40 percent compound annual growth rate through 2017.

Given that these issues are real, how do you address them? I mean, basically, if you look at the above four items as requirements, you need a box that connects the carrier LTE/IMS and policy control environment to existing 2G/3G/Wi-Fi and back office environments. You need a box that bridges different technologies and overcomes incompatibilities through configuration, not R&D. That is a fancy way of saying the use cases need to be considered ahead of time. Dialogic prides itself on any-to-any connectivity, as we have been in this game a long time and provide this service as our business. But even to us, this is not a snap. It’s difficult. Nonetheless, the fast pace of change during the past 15 years proves that the communications industry is up to the challenge. Vendors will solve this problem, and subscribers won’t even know what is happening in the background. They’ll just know it works.  

Jim Machi is vice president of product management at Dialogic Inc. (

Jim Machi is senior vice president of marketing at Dialogic Inc. (

Edited by Stefania Viscusi