A few questions on modem/AT commands
AT commands are an in-band signalling method originally developed for controlling voice modems. They were introduced by Hayes, and were quickly adopted by other modem makers as an industry standard. The basic AT command function is to place the telephone call or terminate it.
Early wireless WAN data modems like CDPD that used serial interfaces emulated AT commands for backwards compatibility, even though they're IP devices. GSM, CDPD's immediate successor, supported them too and they even persist to this day with LTE modems. AT commands can be used to interrogate the device link status like signal strength, IMEI, and other operating parameters.
WLAN (802.11) devices do not support AT commands. Unlike dialup modems, link establishment and management is set up by lower levels of the protocol stack rather than the application, and any control is sent out-of-band. LAN and WLAN controllers provide separate channels for this, such MII that the controller uses to manage the PHY. The MII programmer's model is supported for integrated LAN and WAN as well.