The all-IP (Internet Protocol) world has arrived. Mobile operators worldwide now embrace the IP, whether it’s the rich user experience provided by Wi-Fi or by WiMAX. Existing over-the-top (OTT) clients either work only on Wi-Fi networks with no quality of service (QoS), or few clients that work on bandwidth-limited cellular data network provide a bad Video and Voice over IP (V.VoIP) user experience. With the rapid deployment of Long-Term Evolution (LTE), the time has come for simple and fully integrated dialer-based V.VoIP calls.

V.VoIP isn’t new. It’s been part of the wired cable/DSL world for several years and attained global acceptance. Now, though, after a seemingly long journey, the spotlight is shining on V.VoIP in the mobile arena. Thanks to the GSMA IR.92 Voice-Over-LTE (VoLTE) and GSMA IR.94 IMS profiles for conversational video service—de facto industry standards adopted by the LTE ecosystem in 2010-2011—V.VoIP ensures a rich multimedia experience for mobile users.

A number of key factors contribute to the success of V.VoIP over LTE technology. They include:

“I can hear you and see you in HD quality”

It’s no more “Can you hear me now?” In terms of VoLTE, bandwidth was never a constraint for voice-only service, even during the pre-LTE phase. The concern involved the same pipe being used for both data and V.VoIP real-time communications. With neither QoS nor priority for video and voice, two-way real-time communications can turn into a nightmare. Every meaningful sentence is followed by “Can you hear me?” Thus, any hope of an intelligent conversation becomes impossible. VoLTE guarantees QoS, low latency, and a dedicated bearer with a guaranteed bit rate for HD voice and video call.

A Simple User Interface

Target users typically aren’t technology whizzes or VoIP geeks who know the jargon like VoLTE and IMS. Rather, they’re non-tech, common mobile-phone users. VoLTE accommodates this audience via deep integration of IP communication features with the native dialer. It’s pre-loaded on the handset with over-the-air updates for any subsequent software revisions.

Multiple applications aren’t needed for some of the basic communication features, such as Voice Call, Video Call, Short Message Service (SMS), Multimedia Messaging Service (MMS), Instant Message (IM), Presence, and other IP Multimedia Subsystem (IMS) features. With one simple user interface, users can do it all (see the figure).

Seamless User Experience

Though it’s in early deployment stage and has limited coverage, LTE nonetheless is very important to hand over to the legacy circuit-switched networks in areas that lack LTE coverage. The solution is Circuit-Switched Fallback (CSFB) and Single Radio Voice Call Continuity (SRVCC) as defined by IR.92 standards. This ensures seamless user-experience without any voice breaks when transitioning from LTE to legacy circuit-switched networks.

Most operators will likely launch voice and video services over LTE before they have complete LTE coverage. Others are aggressively deploying VoLTE with fallback to circuit-switched networks where LTE is unavailable. In either case, the bottom line is to create a seamless user experience. Beyond the handoff to legacy circuit-switched networks, an opportunity exists to handoff to controlled Wi-Fi in an enterprise scenario. For example, when moving to an office, a call can be seamlessly transferred to the desk phone.

Priority for V.VoIP on LTE Network

V.VoIP has never had priority on a mobile broadband network. GSMA standards have changed this perspective, but that also spells trouble for V.VoIP OTT applications. Up to now, OTT voice and video applications were having a gala time riding on the operators’ data network. Many customers were left unsatisfied; user expectation was very low with call drops, latencies, and no quality of service. OTT applications will still try to dominate the non-QoS LTE data network while the standards-based VoLTE and Video over LTE enjoy the dedicated bearer that guarantees QoS (for example, operators control a dedicated QoS with LTE).

Finally, operators have found an answer to OTT’s challenge in the form of VoLTE. IP-based calling over the data network posed a threat to the operator community till recent past; with LTE, it’s a big boon.

Ecosystem Commitment

LTE Ecosystem partners, such as operators, equipment manufacturers, device manufacturers, and software vendors, are committed to deliver Video and Voice over LTE. As operators and equipment manufacturers roll out LTE networks, device manufacturers and software vendors keep pace by launching LTE-enabled handsets and VoLTE interoperable software.

In addition to LTE support, today’s smart phones offer front-facing cameras, high-resolution screens, and multiple processors with more than gigahertz horsepower. Combining those features with optimized voice software and integration of video and graphics accelerators guarantees superior multimedia real-time communication.

However, one key question remains: “How ready is the ecosystem?” While VoLTE does require some additional network elements and software, the evolution of the traditional VoIP and IMS-based standards is now coming to fruition. Some, if not all, ecosystem partners have invested in VoIP and IMS the past few years, doing limited trials on existing 3G data and Wi-Fi networks. This has extended the learning curve for ecosystem partners, enabling them to better understand the complexities of tackling real-time voice and video in a wireless environment and address any inherent inefficiencies.


LTE incorporates all of the ingredients needed to deliver that long-anticipated rich multimedia experience—ample bandwidth, guaranteed QoS, and most importantly, a strong commitment from mobile operators. On top of that, the exponential increase of smartphone devices, replete with multiple gigahertz processors integrating high-end graphics, video accelerators, and large screens, further validates user expectations.

Some LTE coverage challenges still must be overcome, though. For example, there’s the issue of coexistence with legacy networks and seamless voice/video across these networks. Nonetheless, LTE is here to stay, and it promises to deliver a superior multimedia V.VoIP experience.