The rise of asynchronous communications such as email and messaging accelerated a long-running decline in the traditional voice phone call. Now, when they occur, synchronous one-to-one voice calls themselves tend to be scheduled rather than spontaneous and perhaps as a result have been largely neglected by mobile operators over recent years.
Yet at the same time, use of voice itself has enjoyed something of a revival in asynchronous mode in various guises, as in personal assistants, remote control for TV services and within user interfaces more generally, and this has been intensified by the pandemic and its stay-at-home scenarios.
This is the background as 5G Voice over New Radio (VoNR) emerges as a sequel to VoLTE (Voice over LTE). It brings new inherent capabilities, but operators seem unenthusiastic about it, preferring to emphasize all the data-related use cases that will be ushered in by 5G. Perhaps more interest will be triggered by a white paper just published by German testing group Rohde & Schwarz. Entitled simply ‘Voice over New Radio’, this outlines technical considerations and relates them to general use cases and also emerging possibilities.
The paper starts off in a slightly defeatist tone by conceding that the main driver behind the development of 5G networks has always been improved data services. The paper then continues defensively by associating voice and video communications as legacy applications, albeit ones still demanded by some subscribers.
The truth is subscribers are demanding them less and less, and the real opportunities around voice and video are for new use cases, or at least extensions of existing ones. The paper does then expand on the capabilities and indicate what some of these might be.
The emergence of voice over IP around two decades ago should have uncorked a new era of innovation around voice services, but instead it merely led to an emulation of circuit-switched calls, which really lasted until VoLTE came along. That in turn, as the R&S paper pointed out, drove adoption in cellular infrastructures of the IP Multimedia Subsystem (IMS), at that stage to overcome technical challenges. But this now provides the foundation for VoNR, as multimedia calls, either voice or video, ride over the IP data connection, managed by the IMS core.
The paper touts the benefit of ultra-high definition for 5G VoNR voice-only calls, but that alone will barely register with users. Indeed, the paper agrees that much more significant is the potential role VoNR can play in hybrid services that include data in conferencing and streaming services. The paper talks about scope for added value from voice on the back of Rich Communications Services (RCS) integration, bringing interactive capabilities, such as real time language translation.
RCS, as well as IMS, has been criticized by some analysts for being associated with dying or uninteresting legacy session-based voice, but that springs from lack of ambition on the part of operators rather than the underlying technology platform. The capabilities are now there with VoNR for a host of media use cases involving voice, and the R&S paper does hint at some of them.
The paper talks about the evolving role of mobile voice in emergency services, recognizing that smart phones are now the device at hand when such calls have to be made. In the early cellular era consumers were instructed to use fixed lines for emergency calls because mobile networks were too unreliable, but now they are by far the most heavily used means of access in these situations.
While incorporation of IMS increased robustness, with various fallback options, 5G brings new possibilities through combining voice, data and video over a single session. This has already been demonstrated in cases such as guiding paramedics through remote ultrasound diagnostics during an emergency on the ground. The higher call quality and low latency can in these situations enhance the use case, so the new capabilities are already making a difference.
Similarly, 5G promises to enhance application of automotive emergency services such as the European Union’s Automotive eCall. Originally, eCall was based on the GSM radio technology, moving to UMTS in later releases. Then the 3GPP specified next generation eCall (NGeCall) under Release 14, moving to LTE instead of GSM, therefore taking the service from circuit-switched to packet-switched voice, and from single voice call to IP data. This allowed the service to start benefiting from more advanced automated capabilities in vehicles, such as transmission of diagnostics that could inform and accelerate responses to breakdowns or accidents.
Of greater interest for many consumers will be what the GSMA and Open Mobile Alliance (OMA) define as supplementary speech services. These include calling party presentation, waiting indication, barring of incoming or outgoing calls, barring of international calls, and easy setup of ad hoc multi-party conferences, all areas where operators have been slow to tap existing capabilities under LTE. Indeed, the GSMA and OMA see the coming of VoNR as a cue for operators to start supporting such services and become more innovative around voice. It is certainly time they did and it is not too late.