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MultiModemISDN User Guide
Data MSN
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The Data MSN (Multiple Subscriber Number) allows a caller to specify an individual MTA128ST-USB
when more than one unit is connected to your network terminator. If you don’t assign a value to the
MSN, the unit accepts all incoming calls. If you only assign a base address to the MSN, the unit
accepts any incoming call with the same base address, regardless of whether a subaddress is
included. If you assign a base address and a subaddress to the MSN, the unit only accepts calls that
match both the base address and the subaddress. The following examples show the syntax for setting
the MSN with and without a subaddress.
AT command: !N1=
MSN with subaddress: AT!N1=5551000:001 (base address is 5551000; subaddress is 001)
MSN without subaddress: AT!N1=5551000 (base address is 5551000)
Voice MSN
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Selects calls on the voice channel in the same way the Data MSN selects calls on the data channel.
AT command: *!N1=
SPIDs and DNs
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For use with North American switches, the Service Profile Identifier (SPID) must be configured in the
MTA128ST-USB. The SPID is assigned by the local phone company and is for the specific BRI line
where the unit is attached. The SPID field is empty prior to configuration.
AT commands
: AT!C6= and AT*!C6=
Directory Number (DN) is the phone number another user calls to contact this unit once it is attached
to the ISDN.
AT commands
: AT!N1= and AT*!N1=
Note: SPIDs and DNs are used only by the U.S. NI-1, AT&T 5ESS, and DMS-100 switch types.
Call Control Configuration
Persistent DTR Dialing
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A high DTR (Data Terminal Ready) signal on the USB port indicates your computer or terminal is ready
to communicate with your MTA128ST-USB. DTR normally goes high when a communication program
starts or is ready to dial. Persistent DTR dialing enables the unit to automatically redial the number
stored in memory location 0 whenever DTR is high and the serial port does not have an active call.
You can enable or disable this feature.
AT command: $D
Auto Answer Data Calls
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Rings to Answer ___________
Select Auto Answer if you want your MTA128ST-USB to automatically answer all incoming data calls
(this option does not affect the analog port). The Rings to Answer number, in the range of 1 to 255,
selects the number of rings the unit waits before answering an incoming call. The default is one ring.
AT command: S0=
Dialing Method
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Select either the Enbloc or the Overlap dialing method for use when establishing a data call. Your
ISDN provider determines the dialing method. The Enbloc method is used for most ISDN dialing;
however, you can select the overlap method if you are working with a private network.
AT command:
%A97=