A session is originated by the application host issuing the ATD (Dial) command:
- ATDP specifies a UDP session.
- nnn.nnn.nnn.nnn is the destination IP address and
- ppppp is the destination application port number.
If no port is specified then a port number of 0 is assumed. It should be noted that UDP and TCP make extensive use of port numbers, please be aware that the modem will use the port number as a criteria for accepting and passing data to the host application.
CONNECT [terse 1] result code will be issued and all ensuing data sent from the host application will be assembled into a UDP packet and transmitted to the destination application.
ERROR [terse 4] result code will be generated if the modem is not currently registered on a CDPD network.
PAD (Packet Assembly and Disassembly) function will transmit data when the inter-character idle time-out occurs or when the PAD buffer is full. (256 or 512 bytes). The idle time-out is specified in register S50 in 1/10 seconds.
Receiving Data - Once the session is started, any packets sent to the modem's IP address with the port number specified in register S110 will be processed and the data portion will be transmitted over the serial link to the host application. Any packets received with a different port number specified will be discarded.
Termination - The session is terminated by dropping DTR or resetting the unit.