Labelling of the default configuration

The * character marks the default AT command settings. The standard values of the individual register bits are marked in bold type.

Incoming calls can be answered using this command. If acknowledgments by the terminal adapter are not suppressed, the result code RING (plain text) or 2 (short form) is displayed for an incoming call. (See $IDIAG? for further information regarding call establishment).

Caution: Calls cannot be answered manually if automatic call answering has been set, as the call establishment will be aborted by the entry of any character other than a line feed (see register S0). Call establishment is not aborted, however, if bit 6 of register S14 has been set to 1 (default = 0). This setting permits the attached computer to send characters to the ISDN terminal adapter during call establishment.

Please also observe the register S152 ("call display delay") with regard to this command. No further commands can be executed from the same command line after this command.

* AT&C1  :  DCD indicates an existing connection

Communications programs normally evaluate the line DCD to verify the presence of a connection. The ISDN terminal adapter supports this evaluation with the setting AT&C1.

When this command is issued, the ISDN terminal adapter attempts to establish a connection and dials the telephone number n. n may consist of the numerals 0 to 9, * and #. The maximum length for the complete dialing string is 36 characters, not including "ATD". The following special characters may be inserted; all other characters will be ignored:

The call establishment can be aborted at any time during the dialing process by entering any character other than line feed, XON or XOFF.

AT$D1  :  disables DTR-dialing

When DTR-dialing is enabled and the condition of the control line switches from OFF to ON, the ISDN terminal adapter establishes a connection to the number stored in the first location (see AT\P or AT&Zcommands). If no number has been stored, the ISDN terminal adapter returns ERROR.

AT&D1  :  switch to command phase if DTR   OFF

* AT&D2  :  abort connection if DTR   OFF

AT&D3  :  abort connection and reinitialize if DTR   OFF

These commands are used to set the response of the ISDN terminal adapter to a transition of the control line DTR from ON to OFF.

With the setting AT&D0, the ISDN terminal adapter ignores the DTR transition from ON to OFF.

With AT&D1, the transition of the DTR control line from ON to OFF has the following effects: If the ISDN terminal adapter is in the command phase, the transition has no effect. During the establishment of a connection, the ON to OFF DTR transition aborts the connection. If the ISDN terminal adapter is in the transmission phase (i.e. with an existing connection), it will switch to the command phase.

With AT&D2, the transition of the DTR control line from ON to OFF has the following effects: If the ISDN terminal adapter is in the command phase, the transition has no effect. During the establishment of a connection, the ON to OFF DTR transition aborts the connection. If the ISDN terminal adapter is in the transmission phase (i.e. with an existing connection), it will abort the connection and switch to the command phase.

With AT&D3 the ISDN terminal adapter's response is the same as with AT&D2. In addition, the ISDN terminal adapter is reinitialized by the DTR transition from ON to OFF (see also ATZ and AT&Y).

With AT&D2 and AT&D3 as well as DTR = OFF, the ISDN terminal adapter does not return a RING for incoming calls. Automatic call answering is not possible until after the DTR transition from OFF to ON. A RING message with subsequent call answering can be enabled despite DTR = OFF by setting bit 7 in register S28.

AT\D1  :  DSR tracks transmission channel and CTS always active

AT\D2  :  DSR always active and CTS tracks DCD

AT\D3  :  DSR tracks transmission channel and CTS tracks DCD

This command affects the significance of the signal lines DSR and CTS. If hardware flow control is used, the AT\D command setting has no effect on the CTS signal line in the transmission phase.

* ATE1  :  commands echoed

This command permits the choice of whether the ISDN terminal adapter returns the input commands as an echo or not.

This is used to load the firmware's default parameter settings. The ISDN terminal adapter is thus reset to its factory defaults. This command is not executed during existing connections.

The dial-number memory, charge statistics, configuration profiles and ISDN settings are not reset by the command AT&F, however.

The dial numbers stored in locations 0 to 9 with the commands AT\P or AT&Z are listed with this command.

This command is used to hang up an existing connection if the ISDN terminal adapter is in the command mode after an escape command or a DTR transition from ON to OFF with a preceding AT&D1.

If ATH2 is input in response to an incoming RING, the caller receives the message "call rejected".

ATI1  :  Report checksum

ATI2  :  Report checksum result (OK or ERROR)

ATI3  :  Report version number and firmware release date

ATI4  :  Display current parameters

ATI5  :  Report serial number and hardware release

ATI6  :  Display product name

ATI7  :  Report self-test result

ATI9  :  Report Plug & Play ID text

This command is used to display the current ISDN parameters.

This command is used to select the operating mode of the ISDN terminal adapter. The ISDN terminal adapter attempts to establish an error-corrected X.75 connection by default. If the remote station does not support X.75, the adapter automatically falls back to HDCLP transparent mode via V.120.

Parameter	Value	Description
<Wert1>	X75	X.75 protocol
	X75T70	T.70NL protocol
	V120	V.120 protocol
	HDLC	HDLC protocol
	TRANS	transparent
	HDLCP	HDLC-PPP protocol
	BTX	X.75, T.70NL and Cept/Kit
	X75FB1	X.75   HDLCP
	X75FB2	X.75   V.120   HDLCP
	X75FB3	X.75   V.120
	V120FB1	V.120   HDLCP

This command is used to select the desired bit rate on the ISDN side. The ISDN terminal adapter operates at a transmission speed of 64.000 bps by default.

AT$ICI=0,0 : Delete charge information

This command is used to display the total connect charges, as well as the connect charges for the previous connection. The charges could be displayed as follows: $ICI:=0,113,1 (113 = total charges, 1 = last connection).

The current-charge display is automatically reset to 0 after the next dialing process. The total-charge information can be deleted with the command AT$ICI=0,0.

This command is used to restrict call answering to specific remote stations (user group) for access protection purposes. If no caller IDs are entered in this table, all calls with a correct service indicator and terminal selection digit or MSN (multiple subscriber number) are reported and a connection established.

If one or more caller IDs are stored, the reporting of the call or establishment of the connection is only effected if the caller ID of the remote station corresponds to one of the stored numbers. A maximum of three caller IDs can be stored. The caller ID may consist of a maximum of 16 digits (0 to 9). All changes are automatically recorded in the non-volatile memory and are preserved until the next change. No further commands can be executed from the same command line after this command. The following settings are valid:

Caller IDs of the remote stations must be stored as follows:

Caller is

- within a private branch exchange : extension number (with terminal selection digit if applicable. e.g. 9820)

- within a city / a country : with area code (e.g. 02416069820)

- international : with country code (e.g. 00492416069820)

AT$ICLI=0,"/" : Suppress caller ID display

This command is only relevant for the DSS1 protocol (Euro-ISDN). If the command is entered in the 1TR6 mode, it will not become valid until switching to the DSS1 protocol. This command determines whether, and if so which, multiple subscriber number (MSN) is indicated as the "caller" during outgoing calls. If a dial number is used which was not assigned to the line, the exchange will automatically insert one of the assigned MSNs. The dial number may consist of a maximum of 20 digits. All changes are automatically recorded in the non-volatile memory and are preserved until the next change. No further commands can be executed from the same command line after this command.

If the command AT$ICLI=0,"/" is used, the dial number display is suppressed by the exchange. This function must be enabled by the ISDN network operator.

This command is used to set the data block length. It can be used to ensure compatibility to other B channel protocols. The following settings are valid:

The command AT$IDIAG? is used to return the adapter's current configuration information.

This command is used to set the D channel protocol. The adjustment may not be made during a connection or with a call pending. All changes are automatically recorded in the non-volatile memory and are preserved until the next change.

NOTE: The DSS1PP may interfere with other units on the same ISDN Basic Rate Interface. This protocol should only be selected when using an ISDN point-to-point connection.

This command is only relevant for the national protocol (1TR6). If the command is entered in the DSS1 mode, it will not become valid until switching to the 1TR6 protocol. This command is used to determine which terminal selection digit should be used to answer incoming calls.

In addition, the terminal selection digit used for outgoing calls is also established. All changes are automatically recorded in the non-volatile memory and are preserved until the next change. The terminal selection digit can be deleted with the command AT$IEAZ=0,"".

The terminal selection digit is accepted as follows:

This command is only relevant for the DSS1 protocol (Euro-ISDN). This command can be used to restrict call answering. If no multiple subscriber number (MSN) is specified here, all calls will be answered, regardless of the target dial number specified for the incoming call. A maximum of three caller IDs can be stored. The caller ID may consist of a maximum of 20 digits (0 to 9). No further commands can be executed from the same command line after this command.

Incoming calls without stated target dial numbers will always be answered. All changes are automatically recorded in the non-volatile memory and are preserved until the next change. The MSN can be deleted with the command AT$IMSN=0,"".

NOTE: MSNs are always stated without country or area codes.

A maximum of three dial numbers can be stored. The dial number may consist of a maximum of 5 digits (0 to 9). All changes are automatically recorded in the non-volatile memory and are preserved until the next change.

This command is used to determine which incoming analog calls will be answered. Changes must be saved with AT*W or AT&W. The following settings are valid:

This command is used to set the bearer capability for outgoing calls. You may select the terminal devices (e.g. telephone or fax) which are to be addressed. Changes must be saved with AT*W or AT&W. The following settings are valid:

AT&M1  :  Synchronous operation

AT&M2  :  Synchronous operation, automatic dialing by DTR   ON

With this command, the ISDN terminal adapter may be used in synchronous mode

NOTE: As synchronous transfers take place in direct mode (without buffering or flow control), the transfer speed corresponds to the ISDN speed after the connection has been established. The transmit and receive clock is thus provided by the terminal adapter.

Bei AT&M1 switches the ISDN terminal adapter into synchronous mode.

AT&M2 corresponds to AT&M1, an automatic dialing takes place at the transition of the control line DTR from OFF to ON, however (see also command AT$D, page*). If no number has been stored, MicroLink ISDN/TLpro returns ERROR.

AT-M1  :  Plain text CONNECT messages independent of AT\V

With the default setting AT-M0, the return of plain text CONNECT messages is dependent on the setting of the command AT\V. The bit rate at which the connection was established is always returned.

The transfer speeds are not differentiated in plain text with the setting AT-M1. (CONNECT messages in short form are identical to those of AT-M0). If the ISDN terminal adapter is configured to ATX0, then the command AT-M has no effect.

The command ATO can be used to switch back into the transfer mode to resume online data transmission if the ISDN terminal adapter is in the command mode after an escape command or a DTR transition from ON to OFF with a preceding AT&D1.

Up to ten dial numbers (m = 0 to 9) can be stored using this command.

The stored numbers n can be dialed using the commands ATDS, ATDS=m, ATD/ or ATD/m. These numbers remain when the terminal adapter is switched off. The command AT\Pm deletes the number stored at location m.

The command AT\P corresponds to the command AT&Z. The numbers stored with the command AT\P can thus be overwritten with the command AT&Z. The number stored at location 0 is also used for automatic dialing with DTR (see AT$D).

The command AT\F can be used to display and verify the stored numbers.

No further commands can be executed from the same command line after the command AT\P.

ATQ1  :  Messages from ISDN terminal adapter on

ATQ2  :  Messages off in answer mode

With this command, messages to the attached computer by the ISDN terminal adapter can be completely suppressed (ATQ1) or suppressed in the answer mode only (ATQ2).

AT*Q1  :  No CONNECT message after invalid escape sequence

The return of the CONNECT message can be suppressed after an invalid escape sequence with this command.

AT\Q1  :  Bidirectional XON/XOFF handshake

AT\Q2  :  Unidirectional CTS handshake

* AT\Q3  :  Bidirectional RTS/CTS handshake

AT\Q4  :  Unidirectional XON/XOFF handshake

This command is used to select a variety of handshake procedures for serial port data flow control.

Data flow control is especially important if the transmission speed to/from the computer is not identical to the speed on the telephone side. This is the case when using error correction and data compression, for example. Without a handshake procedure the danger of a buffer overflow is inevitable.

The data flow in the interface lines is monitored RTS (Request To Send) and CTS (Clear To Send) when using a hardware handshake with the commands AT\Q2 and AT\Q3. Data output to the computer is stopped if the RTS signal line is OFF. The transition to ON permits the output of the received data to continue. If the ISDN terminal adapter continues to receive from the telephone line, the data is temporarily stored in the receive buffer. If the send buffer of the ISDN terminal adapter is full, it switches the CTS (Clear To Send) signal line to OFF, stopping the data output from the computer.

The commands AT\Q1 and AT\Q4 are used to select a software handshake using the XON/XOFF characters. If the ISDN terminal adapter receives the <DC3> character (S-s = XOFF) from the computer, then the data output is stopped until a <DC1> (S-q = XON) is sent. Conversely, the ISDN terminal adapter sends a <DC3> or <DC1> to the computer when a send buffer is full or ready again. Whether the XON and XOFF characters are sent to the ISDN terminal adapter depends on the setting of the command AT\X. They are not sent by default.

In unidirectional handshake processes, the handshake signals issued by the computer are ignored.

ATSn? :  Reads the value of register n

ATSn :  Sets pointer to register n

AT? :  Reads value of last register used

AT=x :  Sets value of last register used to x

The register number n and register value x are returned as a numerical ASCII string. The valid values for x may be restricted (see register S0, for example). Please refer to the chapter "Description of registers" for information on the S registers and the modification of bit-oriented registers. If a register is set to an invalid value, the command is ignored and ERROR returned. If an invalid setting is made in a bit-oriented register, only that particular setting will be ignored; all other valid bits will be accepted.

This command can be used to control the period of time after which the ISDN terminal adapter automatically breaks the connection if no data has been sent in asynchronous mode in the mean time. The default value 0 switches the inactivity timer off.

New firmware can be loaded to the flash ROM using the command AT$UPX. After issuing the command, the firmware file must be sent to the ISDN terminal adapter using the XModem protocol. The firmware file can be found on the CD or diskette which was included with the unit. The current version can be found in our online media (Internet: http://www.elsa.com, GO ELSA in CompuServe).

* ATV1  :  Messages in plain text

This command can be used to select numerical short form or plain text for the messages sent by the ISDN terminal adapter to the attached computer. The messages in short form and plain text are covered in the chapter "Description of messages".

This command is used to display the firmware version of the ISDN terminal adapter.

This command returns the current, as well as the two stored configuration profiles, 0 and 1 (see also commands AT&W and AT*W) of the ISDN terminal adapter.

AT\V1  :  Identification of connections with error correction

AT\V2  :  Additional distinction of correction processes

* AT\V8  :  Detailed CONNECT messages

With the setting AT\V0, call establishment messages are issued in the CONNECT xxxxx form.

With the setting AT\V1, call establishment messages are issued in the CONNECT xxxxx/REL form.

AT\V2 provides additional information regarding the correction process in the form of CONNECT xxxxx/REL-LAPB.

With the configuration AT\V8 the call establishment messages are issued in the CONNECT xxxxx/ISDN/X75 form.

xxxxx stands for the speed with which the connection was established.

Caution: If the ISDN terminal adapter is configured to ATX0 or AT-M1, then the command AT\V will have no effect on the plain text CONNECT messages.

This command is used to save the current configuration of the ISDN terminal adapter. All parameters that were set using AT commands, as well as a number that were set using the S registers are saved. These values are preserved when the terminal adapter is switched off.

Resisters for which the current value cannot be saved using the command AT&W are saved with their default values.

This command is used to save the current configuration of the ISDN terminal adapter. All parameters that were set using AT commands and S registers are saved. These values are preserved when the terminal adapter is switched off.

NOTE: A configuration profile should be saved using the command AT*W.

ATX1  :  Busy signal returns NO CARRIER

ATX2  :  Busy signal returns NO CARRIER

ATX3  :  Busy signal returns BUSY

* ATX4  :  Busy signal returns BUSY

This command can be used to set the terminal adapter to respond to busy signals on outgoing connections with the messages NO CARRIER or BUSY.

1) The command ATX0 is also relevant for messages returned during call establishment. Regardless of the speed or type of connection, only the messages CONNECT (plain text) or 1 (short form) are issued.

AT\X1  :  XON/XOFF characters are sent

This command affects the handling of the XON and XOFF characters used for flow control when XON/XOFF software handshaking is selected (see also AT\Q).

When AT\X0 is set, the XON/XOFF characters are used solely to control the data flow between the local ISDN terminal adapter and the computer and are not sent to the remote system.

When this is set to AT\X1, these characters control the data flow between the local ISDN terminal adapter und computer and are sent to the remote system.

AT&Y1  :  Set pointer to configuration profile to 1

This command is used to set a pointer to one of the two stored configuration profiles (0 or 1). The marked configuration profile is loaded when switching the adapter on or during an initialization triggered by the transition of DTR from ON to OFF (see command AT&D).

If a connection exists it will be aborted. The parameter settings stored with the commands AT&W or AT*W (configuration profile 0 or 1) are then loaded. No further commands can be executed from the same command line after the command AT\P.

AT&Z=n : Store dial number n at location 0

Up to ten dial numbers (m = 0 to 9) can be stored using this command.

The stored numbers n can be dialed using the commands ATDS, ATDS=m, ATD/ or ATD/m. These numbers remain when the terminal adapter is switched off. The command AT\Pm deletes the number stored at location m.

The command AT&Z corresponds to the command AT\P. The numbers stored with the command AT&Z can thus be overwritten with the command AT\P (see also the command AT\P.

The command AT\F can be used to display and verify the stored numbers. The same remarks apply to n as for the command ATD.

No further commands can be executed from the same command line after the command AT&Z.

AT.m? : Reads the value of bit m

ATSn.m=x: Sets the bit m to the value x (m = 0 to 7; x = 0 to 1)

Register values can be changed using this command. The value set for the bit n can be set to the value m in the corresponding register. If access is not permitted, the value in the S register remains unchanged and the ISDN terminal adapter returns ERROR.

Example: If bit 6 is to be set in register S14, then the command ATS14.6=1 must be executed.

If the command AT$IDP=? is entered for example, all valid values for the command AT$IDP are returned.

If, for example, the command AT$IMSN=? is entered, the value range for the ASCII code for the individual characters is returned (48-57 correspond to '0' to '9').