100
MultiModemBA User Guide
DTR Dialing ($D) Command
DTR Dialing is an alternate method of causing the modem to automatically dial a number. Data
Terminal Ready (DTR) is a signal that comes into the modem from the terminal or computer to which
it is connected via pin 20 of the RS-232 interface. In DTR Dialing, the modem will automatically dial a
stored number as soon as it receives a high DTR signal. The DTR Dialing method is popular when
using the modem in synchronous applications.
To enable DTR Dialing, enter command AT$D1 and hit Return. The modem will now dial the phone
number you have stored as N0 when it receives a high DTR signal.
DTR must remain high for the duration of the call, until disconnect. To disable DTR Dialing, enter the
command AT$D0 (or

AT$D

) and hit RETURN.
When you use DTR Dialing, be sure that DIP-Switch #1 is in the UP position, so that DTR is not
forced on. In addition, when using DTR Dialing in a synchronous application, be sure that DIP-Switch
#8 is in the UP position to disable V.25
bis
Command mode.
ITU V.25bis Country Specific Information
Due to the flexibility of the V.25
bis
standard, each country may establish specific regulations
governing the way operations are handled. The purpose of this document is to detail each country's
specific regulations that affect operation of V.25
bis
in Multi-Tech modems.
1. Italy a) Command/Indication modifications
1. Phone number indications include status ;ZPSTTT
a) Z - U, D, or F, for Unrestricted, Delayed or Forbidden
b) P - Delay time if delayed
c) S - Number of retries so far
d) TTT - Interdiction time to further attempts
b) Delayed and Forbidden list behavior
1. 5 retries without delay
2. 2 minute delay between next 4 retries
3. After 9 retries the number is put on the forbidden list
4. 120 minute timer is started on entry to delay list
5. When it runs out, the number is removed from which ever list it is on
c) Auto-Answer mode behavior
1. Auto-Answer in 5 seconds if no DIC
2. Get 10 seconds after DIC to enter CIC
3. If 10 seconds times out then no connection is possible
2. Switzerland
a) Command/Indication modification
1. Modem must remain on-hook for 5 seconds after disconnect
2. Modem must remain on-hook for 5 minutes after 4 consecutive failed calls
3. If modem must remain on-hook, then it is “paused”
4. If the modem is paused and a call is attempted a

PAU

indication is given.
a)

PAUt

Modem is paused for

t

minutes
b) Delayed and Forbidden list behavior
1. 2 minute delay between 4 retries
2. After 4 retries the number is put on the forbidden list
3. The number remains on the forbidden list forever
c) Auto-Answer behavior
1. Auto-Answer mode after 2 rings if no
DIC