Hello,
I have moved slm_shell application t0 a separate thread, including cereg_mon() and slm_shell_data_indication() functions. I can correctly check the SLM (ncs v3.1.1 on nrf9151) responses.
I have modified cereg_mon() to schedule a delayed work, and in that work function I send +cereg=2 command, however, the control is lost: