RE: nRF9151 LTE-M (SDK 2.9.0) – High MQTT publish latency (India roaming eSIM) causing severe battery drain

Simon D-M — Fri, 19 Dec 2025 14:36:12 GMT

Hi Milan,

After simulating your situation on the Online Power Profiler for LTE (It is supposed to be for nrf9160, but the timings are the same), it looks like you are using NB-IoT instead of LTE-M. Your timings correspond perfectly with NB-IoT, and the one you measured in Australia correspond with LTE-M.

Unfortunately, I don't think LTE-M is supported in India (deployment map).

You should be able to see if you are connected to LTE-M or NB-IoT using the Cellular Monitor app under the "Access Technology" (ACT) field.

If you want to learn more about power management, I would recommend taking a look at this "Cellular: Power saving techniques" for the cellular part, and this "Power optimization recommendations" as a more general recommendation.

(We may not be able to respond to you in the next 2 weeks, as we are running low on staff due to Christmas / New Year. Your patience is appreciated. Thanks)

Best regards,

Simon D-M