How to get Kc key and TMSI number with AT command in Linux

I've completely configured the port with opened modem on ttyACM0 as my mobile device (HTC M8). However, it didn't allow me to enter anything. I've tried with hotkey Ctrl-A Z, but there was no news. I don't know how to send an AT command to get more information. If you've done so far, please help me get through this step or it's nice to have any idea.