I am working on low power consumption board around Q2406B.
To get into OFF mode, the external processor lowers ON/~OFF pin and issues +CPOF command. The module returns OK, WIND 8 and sometimes CREG: 0 indications. So far so good, the power consumption drops significally.
To exit the low power mode, the processor rises ON/~OFF pin, but here the results are random. Sometimes the Q2406 enters the desired idle mode, sometimes MAX mode (+CPAS returns 5, AT is functional, but no SIM and network, +CFUN=1 is the solution), and sometimes freezes, and only brute force reset returns it back.
To simplify the problem, I disabled the internal OpenAT appli, WMUX multiplexing and IFC flow control, with no significant change. Also, the use of +CPOF=1 command did not change the behaviour.
I red the Power Consumption Aplication Note and other manuals, tried different hacks, but can get no hints to solve the core problem.