A recent spate of VoLTE launches has put the technology under the spotlight, but its lengthy absence on any meaningful scale – with the possible exception of South Korea – may seem troubling to some industry watchers.
When the original LTE specifications were drawn up, the circuit-switched (CS) domain used in 2G and 3G was dispensed with in favour of an all-IP environment. All well and good, but no provision was made as to how voice and texting – still the two mainstays of a mobile operator’s business – would be delivered over a spanking new all-IP data network.
Circuit-switched fallback (CSFB) is a possible ‘interim’ solution that WCDMA operators can deploy, but it’s hardly ideal. Lengthier call set-up times of around 1-2 seconds probably won’t upset high-spending LTE customers, but call-set up times may be longer if there’s no 3G signal and the call is then directed onto 2G. The 4G voice experience, in such scenarios, is worse than 3G. (more…)
The IP Multimedia Subsystem (IMS) has often struggled to prove its worth to network operators. Despite suppliers’ efforts to extol the technology over the last ten years or so, IMS remains niche.
Sure, an IMS architecture offers the prospect of launching new services more quickly and cost-effectively than is possible with softswitches and TDM kit, but the technology’s business case merits – historically at least – have been far from convincing. Many network operators have generally taken the view it would be too risky to invest in a new architecture to enable additional services that may or may not be commercially successful.
And where IMS has been deployed, it’s the fixed-line players that have done most of the running. Standalone mobile operators, on the whole, have steered clear.
This looks set to change. To plug a gaping gap in the original LTE specification – the lack of a CS (circuit-switched) domain – GSMA recommends an IMS-based approach to VoLTE. (more…)