CertiGuide to A+ (A+ 4 Real)  9  Chapter 1: What are Operating Systems and How Do They Work?       9  Operating System Features            9  The Control Panel

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Advanced Settings - Initialization Commands

Finally the “Advanced” tab allows extra initialization commands to be configured. These will be sent to the modem every time it is first used.

This setting is configured using AT commands, a set of instructions understood by all Hayes compatible modems. In the early 1990’s, during the heyday of dial-up bulletin boards and well before the Internet became popular, knowledge of the AT command set was essential to configure your modem. It has become a lost art over the last decade, but can still be extremely useful. As a practical example, using AT commands it is possible to set many options including phonebook entries, the redial delay and perform a factory reset in case of issues. Consider the AT command set as a valid test topic for A+.

One common use of AT commands is to test a dial-up connection and to see what device is on the other end of a phone line. Some useful AT commands are:

• AT&F: Perform reset to default settings
  
  
• ATH: Hang up/pickup ATH0= Hangup ATH1= Pick up
  
  
• +++: Interrupt current session and access AT command mode
  
  
• ATDT<num>: Dial phone number <num> using tones
  
  
• ATDP<num>: Dial phone number <num> using pulses

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