T-Mobile is planning to support two different network technologies for the IoT but not necessarily equally. As the carrier’s VP of network technology development and strategy explained, T-Mobile is moving forward with an extensive NB-IoT deployment but will only deploy LTE M where it makes sense.

“We will support LTE M also for the use cases that make sense,” T-Mobile’s Karri Kuoppamaki said on the sidelines of the FierceWireless Next-Gen Wireless Networks Summit this week.

T-Mobile in September confirmed it will build a nationwide NB-IoT network next year; at the time the carrier also said it would build an LTE “Cat-M” network next year as well. (Such cellular IoT network technologies have been mired in a slew of acronyms of the years, but most executives today refer to Cat-M as LTE M.)

Kuoppamaki noted that one of the main differences between NB-IoT and LTE M is that LTE M supports voice calls while NB-IoT does not. He noted that both technologies can be deployed mainly through software upgrades, making them much easier to roll out than standard LTE technology, for example, which requires completely new antennas and other hardware.

Kuoppamaki said that voice calls would be an example of a specific use case that T-Mobile might use LTE M to support. He also declined to comment on T-Mobile’s IoT network rollout timeline beyond what the carrier announced in September.

Technologies like NB-IoT and LTE M generally take a slice of the spectrum carriers are using for standard LTE services and apply them specifically to IoT deployments like electricity-meter monitoring. These so-called low-power, wide area network (LPWAN) technologies promise wider coverage areas, better battery life, slower data rates and less expensive service plans than standard LTE options targeting smartphones.

And T-Mobile isn’t alone in deploying LTE network variations targeted at the IoT. Verizon and AT&T earlier this year took the wraps off their own nationwide LTE M networks. And Verizon in September confirmed to FierceWireless that it would begin testing NB-IoT network technology next year, with an eye toward deploying the technology sometime after that. As for Sprint, in May the carrier said it would complete its deployment of LTE Cat 1 technology across its nationwide network by the end of July, and that it would begin deploying LTE Cat M in mid-2018 followed by LTE Cat NB1.

Adding to the complexity in the IoT network market is the fact that Dish Network is also planning to deploy NB-IoT, which many see as a move by the company in part to meet the FCC’s spectrum buildout requirements while it continues to work to ink a sale or lease of its massive spectrum holdings.