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AT Commands
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V.25bis Indications
V.25bis indications are similar to the response codes, sent when your modem is operating in AT
command mode. Six V.25bis indications are supported by your modem:
Verbal Meaning
VAL Command accepted and executed
CNX Connection established
INC Incoming call detected
CFI AB Call failure, abort
CFI ET Call failure, engaged
INV Invalid command
These are the only indications supported by your modem. When operating in asynchronous
V.25bis mode, these indicators are suffixed with Carriage Return and Line Feed characters and
V.25bis indicators will only be sent to your computer if DTR is raised. In certain configurations,
a two letter suffix may be appended to the INV response.
Dialling
Your modem supports two methods of dialling in V.25bis mode; “addressed calling” (similar to
using an ATD command) and “direct calling” (similar to DTR dialling with the &M4 command).
The CRN command is used to initiate a telephone call. The most basic form of the CRN
command is:
CRN number
where the number is the telephone number you are dialling.
For example:
• Type: CRN 01234 <E>
Your modem will dial 01234
If a connection can be made to a remote modem a CNX indicator will be sent by the modem. If a
CFI AB indicator appears, your modem has not been able to make a connection.
To hang up the modem, your computer or communications software must make DTR low.
Dial Modifiers
Dial modifiers are characters than can be included in a phone number to make the modem
perform special tasks while dialling.
For example, not all modem users will be using a dedicated telephone line.
Some users will have their modems connected to PABXs. To allow users of PABXs to operate
their modems successfully, dial modifiers are supported by your modem.