e4d47c27__DataSheet_for_product_XE2422H__description
[pin] 3 [name] /dcd [description] 
/DCD is an active low output from the modem that indicates the presence of a valid carrier signal. The SE2 register controls /DCD in the XE2422H. The default state is for /DCD to be disabled ATSE2=04 enables /DCD.
Cermetek DataSheet for product XE2422H
description