Lab: First connection — annotated AT-command sequence

Lab Scenario: A Smart Meter's First Connection

You are integrating a Quectel BG95-M3 NB-IoT module into a new smart meter design. The meter has been provisioned with a SIM, an APN, and credentials. You will walk through the AT command sequence from power-on to the first MQTT publish — exactly what production firmware would execute. The annotated sequence below shows the commands, expected responses, and timing considerations at each step. Real implementations include error handling, retry logic, and integration with the application processor's state machine; the bare sequence here demonstrates the protocol flow.