RF Circuit

I'm curious about the IC laying on the left of the circuit. The part number has been erased but got a glimpse of it which is from Toshiba. Searched in Toshiba website and found nothing. The IC number is roughly read as "0421MC" or"042LMC". I'm not sure what this IC functions. The 4 connector are VDD, GND, TE, and RXE. There's no oscillator on this circuit and I wonder how could this transceiver circuit works then.

Thank you and goodday.