Airlink RJ-11 manual Modem Signal Behavior

AT Commands

Modem Signal Behavior

The RJ-11 IP Gateway is not a modem (DCE), but is a terminal (DTE) device. It is designed to be connected to another DTE device via RJ-11 cable.The RI (Ring Indicator) signal does not have a corresponding outgoing signal so it is not supported.

Specifically, the DTR, DSR and DCD signals should be crossed with the device as follows:

		Device		RJ-11 IP Gateway
		DCD,DSR		DTR
		DTR		DCD,DSR
To emulate a modem properly, the Host RJ-11 IP Gateway does the following:
Mode	Modem DCD Settings		Behavior
Command/Data	Always on (&C0)		DTR is asserted
Command/Data	Follow connection (&C1)		DTR is asserted only when TCP/IP connection is
			present and has been accepted via ATA or auto-
			answer. DTR is de-asserted when connection is
			lost

The device server monitors its DCD signal in order to detect changes in the device's DTR signal. The following behaviors occur on loss of DCD only.

Mode	Modem DTR Settings	Response to loss of DCD
Offline	AT&D0	Ignore
Offline	AT&D1	Ignore
Offline	AT&D2	Ignore
Online	AT&D0	Ignore
Online	AT&D1	Drop to command mode, preserving connection
Online	AT&D2	Drop to command mode, terminating any connec-
		tion

Phone Numbers

The “phone number” used in an outgoing connection for an “ATD” command may be a real phone number that is translated to an IP/port pair (see Phone Number Translation) or it consists of an IP address and optional port number. All leading non-numeric characters (such as the T or P dial mod- ifiers) are ignored. A number of formats are accepted for the “IP” phone number.

Format	Example	Notes
Dotted decimal	a.b.c.d or 192.168.1.1	Numbers are from 0 to 255
Comma decimal	a,b,c,d or 192,168,1,1	For programs that don't allow dots in phone num-
		bers

Host RJ-11 IP Gateway User Guide, version 43