Voice is seldom discussed any more as a ‘killer app’. The use of mobile voice is declining, because of changing habits and a shift to over-the-top solutions like Skype. As a result, voice is a rapidly dwindling part of MNOs’ revenues in developed markets, and even in emerging economies, where usage remains higher, it is stagnating. However, while most of the 5G conversation is about new levels of data usage, voice is not dead yet. Operators may often give voice away for free as part of a data bundle, but very few have felt able to dump it completely. That entailed complicated and expensive projects to deploy Voice over LTE (VoLTE), because 4G was the first network not to support…