VoLTE challenges will drive carriers to vIMS

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Mobile operators have decided they still need to have their own voice platform, despite the collapse of the business that originally made their fortunes. However, the revenue potential of Voice over LTE (and Voice over WiFi) is limited so it there are two essentials - that voice contributes in other ways to the overall business model, and that deployment is as cost-effective as possible. The latter consideration is proving a major driver for virtualizing the IMS, and NEC's Netcracker division is the latest vendor to address that need.

NEC/Netcracker says its new vIMS offers virtualized control and data plane functions for 3G and VoLTE services, which can be managed from the firm's Network and Service Orchestration platform. This can sharply reduce the cost of VoLTE in particular, as well as allowing for greater optimization, says the company.

These promises will be important to MNOs. While native voice came rather late to the LTE process, VoLTE is now seen by the majority of MNOs as something they have to implement in the next couple of years, even if most of them cannot see a clear profit model. But VoLTE (and Voice over WiFi, which some are using either as an interim step or to fill LTE gaps) are significant deployments with high associated cost and complexity.

Given that, outside of some enterprise applications, it is not obvious that customers will pay for voice any more, high quality voice needs to support the business model in other ways - by keeping customers more visible to the operator, or by improving the overall user experience and therefore reducing churn. And it needs to be affordable.

Whether VoLTE/RCS really can provide something so compelling that users flock back from Skype remains to be seen. At least carriers can minimize the cost and deployment burden somewhat by turning to NFV. vIMS allows both signalling and data transfer functions to be run over a "common virtualization platform" on general purpose servers, which could reduce costs significantly, especially for smaller carriers. IMS functions are deployed as required, depending on service demands, so that the MNO can optimize performance and launch new services easily, while only scaling up as usage requires that.

In a panel at this week's CCA Annual Convention of smaller US carriers, Ericsson's CTO Glenn Laxdal said the benefits of virtualization were applicable to tier two and three operators, not just the big firms which are leading the way. The panel agreed that some network functions lent themselves to virtualization more than others with vIMS being selected as one of the best use cases. For a smaller carrier, Laxdal said this could be a more affordable way to launch VoLTE even to smaller numbers of subscribers. The other element which he recommended as a first step to virtualization was the EPC.

So far, virtualized IMS and VoLTE deployments have been the preserve of the tier one pioneers such as Telekom Austria (also working with Netcracker) and AT&T.

AT&T, which has a sweeping program for virtualization and software defined networking (SDN), said last year, ahead of its VoLTE launch: 'The underlying network to support Voice over LTE and the IMS piece of that will be virtualized and will run in a cloud."

Virtualized, outsourced VoLTE has also been on display at Russian operator MTS, which has been using Nokia's telco cloud infrastructure. This cloud-based system includes a full voice core with IMS, Telephony Application Server and HSS.

And IT companies are announcing NFV versions of their products to make the path to IMS and VoLTE a less daunting one for carriers.

But all the benefits of virtualization do not remove the need to invest heavily in the network to support the kind of QoS that will be necessary to differentiate from over-the-top options.

First, it will require carriers to intensify their RAN build-out, since they will need full coverage and, in many cases, denser cells for guaranteed hand-off and QoS (though WiFi Calling is a useful gap-filler, it also requires IMS). Where VoLTE is well implemented on a dense network, superior voice quality is generally reported compared to legacy circuit switched systems or the vagaries of OTT services. However, for most MNOs, it will be years before they achieve that kind of density over a majority of their coverage areas, and so they will have to maintain dual systems - and their customers will have to tolerate fallback to 2G/3G - for a long time, adding to cost and to QoS issues.

Huawei has already said that MNOs will need 'VoLTE Plus', which will appear from 2016, to deliver truly superior services. This will address uplink rates, density and also the risk of signalling storms, a factor which will drive the need for more investment in IP infrastructure and Diameter routers.

And second, it will need to provide services that users genuinely want, to avoid becoming merely a cost incurred for a dying service carriers just can't bear to let go. Call forwarding, video chat, unified voicemail boxes … these just don't seem exciting enough to lure customers away from free services any time soon.

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