An apparatus and method for transmitting serial digital data across wireless modems is disclosed. In one embodiment, data is collected by a remote monitoring device and transmitted to a first Cellular Digital Packet Data (“CDPD”) modem via one or more RS232 interfaces. The applications program in the first CDPD modem transmits a signal to a second CDPD modem initiating communications. The applications program in the second CDPD modem returns a signal, indicating the status of the interface. Data transmission is initiated when the status of both interfaces is established.