AT&T isn’t revealing too many specifics about when it will use low-band spectrum for its 5G deployment but confirmed that it likely will start deploying low band for 5G next year.

While T-Mobile is banking on its heavy reservoir of 600 MHz for its 5G deployment, AT&T and Verizon have been focused on millimeter wave (mmWave)—mostly 39 GHz and 28 GHz, respectively—for their initial 5G deployments. But there will come a time when AT&T starts to refarm its lower-band spectrum for 5G.

“While we haven’t yet disclosed which specific spectrum bands we’ll be using for 5G beyond our initial mmWave deployments, we definitely intend to use lower bands as anchors for mobile 5G in addition to mmWave,” said AT&T’s Gordon Mansfield, vice president Converged Access and Device Technology, in a statement provided to FierceWirelessTech.

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“We’ll let the market and our customers determine the pace at which we deploy that additional spectrum. These lower bands have different propagation characteristics vs. mmWave, such as longer transmission distances and better penetration through buildings and other obstructions,” which makes them a strong complement, according to Mansfield. “While we don’t have a specific deployment timeline for low-band spectrum, we’ll likely start deploying it next year as compatible chipsets become available.”

The topic came up during a conference call Wednesday between industry analysts and AT&T CTO and President of AT&T Labs Andre Fuetsch, who said AT&T will use its sub-6 GHz for 5G in 2019 when the chipsets to support it and mmWave become available in devices, according to Susan Welsh de Grimaldo, director at Strategy Analytics, who participated in the call.

Great to have @ATT CTO Andre Fuetsch confirm that AT&T will be refarming slivers of its low band spectrum to support 5G smartphones when they are commercially available in 2019. Low band will be

anchor band for mobile 5G - adding low latency benefits to LTE Advanced Speed — SusanWelshdeGrimaldo (@SWdeG) September 27, 2018

AT&T’s initial launch of 5G in 2018 is centered on the 39 GHz band, which is good for high speeds and low latency in urban hot spot zones, but due to its limited propagation is not economical to blanket large areas with mmWave coverage—and it will have more limited coverage in-building, Welsh de Grimaldo noted.

5G smartphones are not expected to commercially launch until sometime in the first half of next year.

“Competitively, AT&T needs to have broader 5G coverage for smartphones than it will deploy with its 39 GHz spectrum,” she said via email. “As T-Mobile is launching 5G with its 600 MHz band and Sprint will be using its 2.5 GHz band, they will be able to deliver a much better coverage with these bands that propagate better over larger distances—particularly the 600 MHz band—than any mmwave deployments.”

RELATED: Verizon sees refarming as ‘a capacity solution where the company lacks AWS-3 spectrum’: Jefferies

AT&T has an assortment of lower-band spectrum at its disposal. The operator’s LTE network primarily works on its AWS-1 and 700 MHz spectrum licenses, but can also stretch into its WCS holdings and other spectrum bands.

Fuetsch told analysts that the sub-6 GHz radios that AT&T has been deploying this year are all 5G ready and thus 5G can be turned on through software, and the spectrum can be incrementally refarmed in small slivers at a time as more people upgrade to 5G phones and as usage increases capacity needs. The initial sliver of lower band spectrum will serve as a 5G anchor layer for broader coverage to add an improved latency, and devices will connect to AT&T’s 5G Evolution (its name for its 4G LTE Advanced) that it has already been building out to provide high speed coverage widely, and use 39 GHz 5G for a more consistent higher speed experience in areas with high concentrations of users, Welsh de Grimaldo said.

“For all the carriers, LTE-Advanced is a crucial part of their 5G story,” she added.