While Sprint and T-Mobile are busy campaigning hard for their proposed merger, they’re compelled to conduct business as normal for the time being, and when it comes to VoLTE, Sprint is still in a holding pattern in terms of a national commercial release.

However, a spokesperson told FierceWirelessTech that Sprint plans to be the first carrier to launch VoLTE on a fully virtualized core when it conducts a commercial launch nationally this year.

“We’ve delivered a very good voice experience on an efficient wireless network platform and wanted to be sure of the quality of experience before transitioning to VoLTE,” said spokeswoman Roni Singleton. “Currently, we’re testing our new VoLTE network in more than half our markets on the newest VoLTE-capable devices. We’ll be the first carrier to launch VoLTE on a fully virtualized core when we do our commercial launch nationally this year.”

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Last year, Sprint said it was testing VoLTE and preseeding the customer base with VoLTE-capable devices in preparation for a commercial deployment starting last fall. The plan was to match its current HD Voice experience with a high-quality VoLTE experience.

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Over at would-be merger partner T-Mobile, executives have boasted about how the “un-carrier” was first in the U.S. to deploy VoLTE. As of the first quarter of 2019, VoLTE comprised 88% of total voice calls, up from 87% y/o/y in the fourth-quarter of 2018 and 80% y/o/y in the first quarter of 2018, according to T-Mobile’s Investor Factbook (PDF).

One of the issues for Sprint is that its current LTE network covers far fewer square miles and POPs than rivals AT&T and Verizon. In an April 15 filing (PDF) with the FCC, Sprint noted that one of the problems it faces with respect to the customer experience is it relies on CDMA for voice, and for that reason, most of its users can’t use voice and data at the same time—and they won’t be able to do so until the migration to VoLTE.

U.S. Cellular, which is similar to Sprint in that it’s a CDMA carrier, also is involved in a multi-year VoLTE program. U.S. Cellular expects to have its entire footprint VoLTE-completed by the end of 2020 or early 2021, CTO Mike Irizarry said during the company’s latest quarterly conference call with investors earlier this month.

RELATED: VoLTE spreads to Sprint and smaller carriers like Bluegrass, Southern Linc and others

U.S. Cellular President and CEO Kenneth Meyers also said during the call that from a network perspective, just because it has VoLTE everywhere by that time doesn’t mean it’s necessarily going to turn off the CDMA network. “It's going to be a matter of how much traffic is still being utilized on the small amount of spectrum that we have dedicated to it,” he said, according to a Seeking Alpha transcript. “And that will be a 'then' type of decision.”