The rollout of 4G was hastened by the ability to offload (via CSFB) the complicated issue of handling voice calls onto the established world of 3G. But the fix is running out of time.
Sometimes, communications industry news goes mainstream, with stories that usually concern mainly industry professionals finding their way into the national media. This was the case last week, with Vodafone’s sunsetting of its 3G network reported by BBC News. The angle taken was broadly one of customers who’d have their Internet access compromised by the shift to next generation networks (4G and 5G). You can read it all here.
From inside the industry, the importance of the news and the story itself is, perhaps, quite different. Why? We’d argue that one way you could interpret news of the closure of 3G networks is primarily as a story about 4G voice. Circuit switched networking (of which 3G was the final iteration) was designed for voice and did the job of voice transport, as you’d expect, very well. However, as we also now know, appetites for data have boomed since the early 2010s and innovation has since then been driven by the need to accommodate and enable far greater data usage and volumes with far less focus on traditional voice services.
To address the newly emerging equation, change was needed, and it took the form of (first) 4G, the first purpose-bult data-first network. In 4G (unlike 3G) technology, IMS acts as the control platform rather than the circuit switch. This meant next generation data services were enabled and moved front and centre of the commercial opportunity. But what about voice? There was a story here because 4G was (and is) no more optimised for voice than 3G was for data.
The solution to the problem to date has been a workaround: Circuit Switch Fallback (CFSB), a mechanism that enables voice and SMS to function as normal in 4G networks, using legacy 2- and 3G systems. CSFB has meant carriers could exploit the new data opportunities while continuing to leverage their “old” networks to transport voice. But now there’s a problem. It comes because 3G networks are being closed down. So CSFB won’t work anymore. That being the case, what happens to voice?
The fly in the ointment
First, why is the sunsetting of 3G happening right now? The answer to that question is mainly related to spectrum availability. To accommodate new (5G) services, existing 3G spectrum must be made available and re-purposed, and this can only be achieved by closing 3G networks. Once their spectrum is freed up, 5G can roll out at pace.
But where does this leave voice? With the closure of 3G networks, as we’ve already said the CSFB workaround disappears and suddenly the challenge of transporting voice over the data network becomes unavoidable because it can no longer be offset. That’s the point in time we’re fast approaching today.
So, what about voice?
What to do? CSFB was always likely to be only a temporary measure, favoured mainly because it sped up the deployment of 4G networks by overcoming an immediate problem.
By 2015 a more permanent solution to emerged, Voice over LTE. VoLTE was introduced as an extension to LTE (one of many 4G network variants) but, by and large – outside of a small number of carriers in the US -, no one deployed it. Operators preferred CSFB and they were in no rush to discontinue it both because it worked, and also because VoLTE is complicated to deploy. As long as 3G networks were maintained, VoLTE was an avoidable challenge.
Not anymore. Today, carriers must get to grips with VoLTE and in particular VoLTE roaming because doing so can no longer be postponed (unless they want voice services to disappear from their offering altogether). In consequence, the GSMA is leading the way to define approaches that might smooth the transition.
From an industry perspective, that may be the real story behind the national media headlines about disappearing 3G internet access. We’ll look further into VoLTE and what’s likely to change in a future blog. But for now, it’s safe to say a new set of opportunities for solutions vendors in areas like VoLTE and roaming are fast coming to the fore.