N O V A T E L W I R E L E S S T E C H N O L O G I E S L T D .
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A T C o m m a n d S p e c i f i c a t i o n - E x p e d i t e a n d M e r l i n
W i r e l e s s I P M o d e m s
Dial (Connection Setup)
Description:
In wire-line modems a connection s made when the modem is instructed to dial a telephone number for
the desired computer service. This dial command ATD provides the user with the means of using either
tone dialing, ATDT, or pulse dialing, ATDP. For wireless Internet modems using CDPD technology, the
ATD command is used to initiate a session with a remote Internet server using either TCP/IP or UDP.
Instead of a phone number, an IP address is used instead. It is here that the use of the Internet makes
CDPD easy to use as there are no area codes, no country codes, no need to access an outside line. All
IP addresses currently use a fixed length series of four numbers separated by dots.
The Dial Connection Setup command causes the NRM to establish a connection with the host at the
specified IP address/port. For any fields that are left blank, values are taken from those stored in the
default destination register. The NRM will not process this command if the DTR line is not asserted (i.e.
an ERROR response is issued). It is recommended that the host application make sure the modem is
connected to the network before issuing a Dial command.
Format:
ATDT<IPaddress>/<port#>
To initiate a TCP Session
ATDP<IPaddress>/<port#>
To initiate a UDP Connection
ATDN<Ipaddress>
To initiate a Telnet Session. Port 23 is assumed.
ATD
To use the Default Register
IPaddress format
XXX.XXX.XXX.XXX
where XXX is a number [0 to 255]
port# format
XXXXX
where XXXXX is a number [0 to 65535]
Examples
TCP Connect
ATDT166.1.109.3
(no port given, 0 assumed)
IP = 166.1.109.3
Port = 0
UDP Connect
ATDP166.1.109.3/55000 (Port number specified)
IP = 166.1.109.3
Port = 55000
Default Connection
ADT
(S53=P166.1.109.3/55000)
Same effect as above
Validity:
This command is valid for AT Command mode only.
