VoLTE Will Drive Mobile Carrier Adoption of IMS

Carl Weinschenk

Carl Weinschenk spoke with Joe Hoffman, ABI Research’s principal analyst for mobile networks. Hoffman’s report, “Does VoLTE Provide the Necessary Impetus for IMS Growth in Mobile?” was published on Oct. 10.

To date, the use of the IP Multimedia Subsystem — IMS — has been dominated by wireline networks. For them, the rationale is straightforward. The emergence of Voice over LTE will give mobile operators the push they need to jump in more fully, said Joe Hoffman. He told IT Business Edge blogger Carl Weinschenk that the efficiencies of combining voice and data on one network will prove compelling to wireless carriers over the long haul.

Weinschenk: What is driving mobile interest in the IP Multimedia Subsystem (IMS)?

Hoffman: One of the key drivers I think is operators are looking to avoid inefficiencies. In the North American market, LTE is data-only and 3G is voice and data. Verizon, for example, has a voice network that is CDMA 1x. In LTE, they use VoIP or other techniques to offer voice. Operators are looking to change that with IMS. We wanted to identify how they are doing that.

Weinschenk: So IMS is the road to a combined voice and data network.

Hoffman: IMS is the standard agreed upon that will eventually determine how to handle voice over LTE (VoLTE) and SMS traffic as well. It points to maximal utilization of hardware and spectrum investments.

In the research, we wanted to get several different perspectives on where operators are and when the ecosystem will take off for mobile LTE IMS. It is there for fixed networks, and is growing for them at a steady pace. In mobile networks, it hasn’t really taken off because they had a workable solution for voice and SMS in 3G. The driver to take on the added complexity and cost case wasn’t there.

Weinschenk: But that hybrid network is growing too inefficient.

Hoffman: Now they are thinking about IMS in the context of 4G coming on board with all data efficiencies and to keep aligned with worldwide standards from the GSM Association, whose version of voice over LTE we think is going to play a dominant role. It has all the ecosystem advantages. I think we’re past the tipping point on that.

I think IMS is in good shape. I think, what we see now is the rocks in the creek of getting it launched. We see this version moving up slowly, but not because the market is not there. They had an issue of getting LTE out there. We see some change of timeframes because of different issues. For instance, what does a Sprint and Softbank deal mean? Acquisitions tend to put capital on hold. We saw that with T-Mobile and AT&T. That seemed to slow things down. These things tend to be complicating factors.

Weinschenk: So the current numbers of the use of IMS for mobile will start ratcheting up, but not yet.

Hoffman: We are at the very introduction for revenue numbers. Subscriber numbers are so low that any pause makes it look bad. That’s in the near term. We are in the flat part of a curve.

I think overall the attitude is conservative and cautious. They are saying IMS is a valuable thing. We have 4G and there are many rich opportunities. Who will be on the leading edge or be second — or fast — followers? There are a lot of opportunities. People are waiting. The key thing will be the arrival of handsets supporting Single Radio-Voice Call Continuity — SR-VCC — which allows easy handoff to 3G when the user is out of 4G range. Those chips are in various stages of development and I think samples are available now.

Weinschenk: Is IMS starting to be seen as a necessity for mobile?

Hoffman: They can envision the richness of what will happen with IMS. We can see the richness in over-the-top applications [offered on a piecemeal basis by third parties]. It is hard to visualize what will be the case when there is standardization. All the OTT applications work great when the networks are not heavily loaded. We will see traffic continue to explode as carriers offer applications. That’s where operators will be able to show the real value of being able to manage that traffic using IMS.

Weinschenk: Will IMS, since it is in the core of the network and can manage packets as they flow by, play a role in fulfilling Net Neutrality obligations?

Hoffman: I think IMS is a new tool in operators’ toolkit. How it will play out is not clear, but it gives them additional approaches.

Weinschenk: Is voice over LTE — VoLTE — the killer app that will justify IMS for mobile?

Hoffman: Voice traffic is pretty much table stakes. At the end of the day, we are looking at growth of traffic that will be data-oriented. In the future, you have to go to bits instead of traditional approaches to voice. That’s where traffic is going, so that’s where the money going — and that’s where IMS’ value is.

Weinschenk: How is the wireline side of IMS progressing?

Hoffman: Wireline is showing steady growth as non-traditional operators such as cable companies use it for their voice traffic. We found that in a five-year timeframe the distribution will be 50/50 between IMS on mobile and fixed networks. Right now only 8 or 9 percent of the IMS networks out there are supporting wireless. Seventy-five percent of subscribers served by IMS are on fixed networks. Wired networks use it first because it is straightforward. Those are continuing to grow, but 4G on LTE will kick in gear on mobile networks because of VoLTE.

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