Yes, the chip (or sub-chip) in your phone that talks to the mobile network is still called a modem, and is still controlled with the AT command set. When you answer a call it sends "ata" (AT Answer) to the modem. It does not pick up AT commands from the data passing through, unlike the old modems.
I installed https://github.com/SecUpwN/Android-IMSI-Catcher-Detector the other day and found a menu entry called "AT command interface", which I shall carefully leave alone.