Ericsson and Qualcomm have revealed the first successful attempt at making a 4G voice connection switch over to 3G without dropping the call.
The handover between LTE and WCDMA took place on 23 December last year, but was only announced on Thursday. The event was a demonstration of the technical abilities of Ericsson's network equipment and a Qualcomm LTE/3G multimode smartphone chipset, and makes the idea of voice-over-LTE more viable than before.
"By accomplishing this advanced LTE handover technology together with Qualcomm, we now ensure that operators can meet consumers' expectations on a high-quality voice over LTE service," Ericsson's networking chief Johan Wibergh said in a statement. "Operators will be able to maintain their quality brand for their voice business when they launch voice over LTE."
Voice over LTE (VoLTE) has so far been something of a missing link in the 4G LTE deployments that have taken place. Operators have avoided implementing the all-IP voice capabilities in the LTE standard because when the user moves out of LTE coverage, the call will be dropped.
For this reason, companies making LTE handsets have to build legacy circuit-switched voice technology into each device. Last September, Research In Motion's radio standards chief gave this as a major reason why there are no LTE-capable BlackBerry smartphones yet.
Given the wide spread of 3G coverage, falling back from LTE to the 3G technology WCDMA is a major step. However, it is still not possible to have an LTE call hand over to the even more ubiquitous GSM, or 2G.
"This is the first time we have done [a handover] with a 3G network because that is the most demanding side [to work out]," an Ericsson spokeswoman told ZDNet UK on Friday. "We're working on the 2G handover as well."
In Qualcomm's latest quarterly results, released on Wednesday showing a 40 percent boost in revenue and a 20 percent rise in profit, the chipmaker said it was "excited" about 4G deployments and about continuing 3G rollouts around the world.
Qualcomm is on track to sample its 28nm MSM 8930 Snapdragon chipset, which "will enable 3G/LTE smartphones at high-volume price points", chief operating officer Steve Mollenkopf said in an earnings call.
Ericsson said it expected its Single Radio Voice Call Continuity (SRVCC) kit, which was used in the demonstration, to be deployed from later this year.
There are now 29 countries with commercially active LTE networks, but the UK is not one of them. Squabbling between operators and the regulator Ofcom have caused multiple delays in the 4G auction that will sell off the relevant spectrum, although recent proposals from Ofcom may clear the deadlock.
Everything Everywhere has also requested that Ofcom allow UK operators to reuse their 2G spectrum for 4G services, where possible.
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