how did you enter for +CPSMS?
It should be something like this:
14:29:15.501 on 08-Mar-2021> AT+CEREG=4
14:29:15.534 on 08-Mar-2021>
14:29:15.713 on 08-Mar-2021> OK
14:29:15.725 on 08-Mar-2021>
14:29:15.815 on 08-Mar-2021> +CEREG: 0
14:29:15.827 on 08-Mar-2021>
14:29:15.838 on 08-Mar-2021> +CREG: 0
14:29:15.849 on 08-Mar-2021>
14:29:15.877 on 08-Mar-2021> +CEREG: 2
14:29:15.887 on 08-Mar-2021>
14:29:15.895 on 08-Mar-2021> +CREG: 2
14:29:15.906 on 08-Mar-2021>
14:29:16.93 on 08-Mar-2021> +CEREG: 1,"0001","01A2D001",7,,,"00001010","00111001"
14:29:16.137 on 08-Mar-2021>
14:29:16.145 on 08-Mar-2021> +CREG: 1,"0001","01A2D001",7
14:29:16.197 on 08-Mar-2021>
14:29:17.279 on 08-Mar-2021> +SIM: 0
14:29:17.288 on 08-Mar-2021> AT+KSLEEP=1,2
14:29:17.556 on 08-Mar-2021>
14:29:17.564 on 08-Mar-2021> OK
14:29:17.573 on 08-Mar-2021> AT+CPSMS=1,"11100000","11100000","00111001","00001010"
14:29:19.670 on 08-Mar-2021>
14:29:19.682 on 08-Mar-2021> OK
14:29:19.695 on 08-Mar-2021>
14:29:46.160 on 08-Mar-2021> +CEREG: 4,,,,,,"00001010","00111001"
14:29:46.180 on 08-Mar-2021>
14:29:46.214 on 08-Mar-2021> +CREG: 4
Precisely, these values are to have modifications on the TAU on behalf of the network.
The network adds between 40 and 50 minutes to the requested TAU.
The HL78 receive from the network this TAU value, because he sleep between 41 and 51 minutes.
So my question is : If the HL78 sleep during the network TAU value, how i could retrieve this value ?
I’ve try other TAU value greater than 45 minutes, but the “+cereg: 4” message is the same !