LTE: Breathing New Life into IMS?

IMS (IP Multimedia Subsystem) is back in the news! Remember IMS? There was a lot of hype around it a few years back, then came a big reality check (e.g. how can the cost of deployment be justified?), and in the end just a few operators decided to roll out IMS in earnest (and indeed Comptel was part of some of those successful deployments).

So, why is it in the news again?

The main reason why IMS is currently making headlines is LTE (Long Term Evolution): the new mobile technology that effectively brings in IMS. This has led some observers to declare that IMS is nowhere at the moment but will be everywhere once LTE comes in. Now I don’t see it that way—far from a big bang, the introduction of IMS is and will remain to be a slow and incremental process. I would like to explain why.

Firstly and most importantly, I believe that the foundations for IMS are already being laid now at many mobile operators, because of factors that are not directly related to LTE. The massive increase in mobile broadband and the development of packet core networks is moving the industry slowly but inevitably towards an IMS type of all-IP environment. To an OSS/BSS vendor like Comptel, this can be witnessed relatively easily by the amount of work done around DIAMETER and various DIAMETER protocol implementations. We see that, for example, in various policy control approaches taken by most mobile operators, such as AT&T (which I blogged about recently) or the Comptel Roaming Cost Control implementation at DNA Finland. DIAMETER is not necessarily the de-facto standard yet, but it seems that more and more equipment supports DIAMETER as the ‘standard’ protocol for usage charging or policy management. And this is key to IMS succeeding; DIAMETER is part of the IMS architecture.

Another factor driving the progressive evolution to IMS is the growing interest in using user data for active decision-making in OSS/BSS. I have already mentioned policy control, but we are also seeing an increased need for customer-centric fulfilment and charging. And, this is mirrored by the evolving role of customer information repositories, such as GUP (Generic User Profile), SPR (Subscriber Profile Repository), HSS (Home Subscriber Server) and HLR (Home Location Register) and others, as well as the significantly increased awareness and adoption of 3GPP-aligned strategies. So while data management is still a major challenge and synching all repositories is still a major headache, there is no doubt that customer data and intelligence are moving towards the network—as IMS requires it.

That said, while there is clear evidence that the foundations are already being laid pre-LTE, I also believe that when operators do eventually deploy LTE, they will not go to an all-IMS architecture straight away. The main reason for this is that operators are unlikely to do a wholesale replacement of their established 2.5 and 3G networks. The fact is that, despite the growth in data, revenue is still mostly made with voice, and voice does not really need an all-IP environment. The Circuit Switched (CS) core is still there, and why not use it? Just like PSTN, the CS core will be more or less a place where no new investments are made, and if they are made, it’s because the new stuff is substantially lower-cost, if nothing else. Furthermore, while IP core is struggling to cope with the smartphone load of IP traffic, I would think that operators would be adopting the wrong strategy if they put their money making voice onto an overloaded (or soon-to-be overloaded) IP network. There may be a time when it will make economic sense to move to an all-IP network, but operators will also be keeping a CS network. And that also means that IMS will have to sit alongside more traditional and indeed legacy systems.

There is one final factor that I would like to highlight: China. While the rest of the world is contemplating a move to IMS, China Mobile and more recently China Telecom are boldly going where virtually no other has before—a large scale, nationwide IMS infrastructure. In my opinion, aside from the example it sets, this will mean that some vendors who supply the network-side kits to this investment will be in a fairly strong position in the future, having gained invaluable experience, and that will serve to reassure other telcos about IMS. This move will impact the telco sector much more than we can even imagine today.

In short, I believe we are unlikely to see a mad rush to IMS, just a slow and steady adoption as we have seen up to now.

In reality, neither IMS nor LTE (or any other technology) matters really. What matters is that we, the users, get the services we want at a price we’re willing to pay for with devices and technology supporting it. If IMS or LTE are the technologies that can deliver the necessary capacity, experience, latency or whatever functionalities (or not) needed, while balancing operators’ costs so that they can continue to build more, then they will be adopted. If not, they will fail and be hyped about for awhile and forgotten.