T-Mobile US CTO Neville Ray claimed the operator was the first in the country to test narrowband-IoT (NB-IoT) in guard bands.

3GPP specifications for NB-IoT outline three deployment scenarios: in band; standalone; and guard band. In band deployments use the same spectrum which carries LTE traffic, while standalone scenarios employ a new chunk of unused spectrum. Guard band deployments push operation out of the LTE bands and into the untapped spectrum in-between radio bands which is typically reserved to protect against interference.

Ray noted on Twitter “operating in guard bands is one of NB-IoT’s greatest benefits because the traffic doesn’t compete with other customers’ data”. The operator did not immediately respond to a request for more information about its plans for NB-IoT in guard bands.

T-Mobile rolled out live NB-IoT in Las Vegas, Nevada, in October 2017 and plans to deploy the technology nationwide by the middle of this year. At Mobile World Congress Americas in September 2017, SVP of technology Dave Mayo told Mobile World Live the operator chose NB-IoT over other IoT technologies because it uses less spectrum. LTE Cat-M1 (LTE-M) “requires you to dedicate big blocks of spectrum” he explained, adding the operator believed NB-IoT “was a better match for the spectrum resources” it planned to use.

The operator in January took aim at its rivals with a new IoT business tariff it said undercut Verizon’s LTE-M prices. At the time, T-Mobile noted “NB-IoT carries data with greater efficiency and performance” than LTE-M.