Hanging Up,  | 
  | You  | 
  | can  | make  | the  | command  | modem  | hang  | up  | 
  | (go  | On  | 
  | 
  | Hook),  | or  | |||||||||||
and  | 
  | go  | Off  | Hook,  | with  | the  | 
  | H  | command.  | Entering  | ATH1 | (upper  | case)  | |||||||||||||||
Bringing the  | 
  | will bring the line Off Hook just as if you had picked up the  | 
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Phone Line  | 
  | telephone handset. The command modem remains in command  | 
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Off Hook  | 
  | mode.  | 
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  | You  | 
  | can  | hang  | up  | by  | entering  | ATH0 | or  | ATH  | (remember  | that  | 
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  | default value is 0 when nothing is entered). It is not necessary to  | 
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  | use the H1command to  | ||||||||||||||||||||||
bring the line Off Hook when using the  | 
  | command modem D command to dial,since the modem will  | 
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off hook automatically when you hit  | Return at the end of  | 
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  | the Dial command.  | 
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Inquiry for  | 
  | Some  | 
  | systems  | or  | software  | 
  | packages  | may  | 
  | automatically  | 
  | check  | |||||||||||||||
Product  | 
  | the  | 
  | “identification”  | of  | the  | modem  | with  | which  | they  | are  | 
  | communicat-  | |||||||||||||||
Code | 
  | ing,  | 
  | by  | 
  | using  | the I command. This “read” command  | 
  | enables  | 
  | the  | |||||||||||||||||
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  | software  | to  | determine  | the  | type  | of  | modem  | with  | which  | it  | 
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  | is  | commu-  | |||||||||||||
I  | 
  | nicating.  | 
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  | When ATI or ATI0 (upper case) is entered, the command modem  | 
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  | will respond with xxx,  | |||||||||||||||||||||||
with the first two digits indicating model, and  | 
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  | the third digit indicating the revision level.  | 
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Exiting  | 
  | You  | 
  | can  | bring  | the  | command  | modem  | out  | of  | command  | 
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  | mode  | back  | |||||||||||||
Command  | 
  | into  | 
  | the  | 
  | Mode,  | by  | entering  | ATO | (where  | O  | is  | the  | letter  | O,  | |||||||||||||
Mode, | 
  | not  | 
  | the  | 
  | number  | 0).  | In  | this  | case,  | the  | O  | command  | reverses  | what  | |||||||||||||
Going Back  | 
  | was  | 
  | done  | 
  | by  | entering  | the  | Escape code  | 
  | (see  | Escape  | 
  | 
  | Code  | 
  | +++  | |||||||||||
  | explanation).  | 
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Pulse or  | 
  | The  | 
  | command  | modem  | will  | dial  | numbers  | using  | either  | 
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  | pulse  | or  | ||||||||||||||
Tone  | 
  | tone  | dialing,  | or  | in  | a  | combination  | of  | both  | methods.  | Pulse  | dialing  | ||||||||||||||||
Dialing | 
  | is the method used by   | 
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  | timed  | 
  | opening  | and  | |||||||||||||||||||
closing  | of  | 
  | a  | 
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  | line  | relay.  | 
  | Tone  | 
  | dialing  | 
  | is  | 
  | that  | 
  | used  | |||||||||||
P  | 
  | by push button   | 
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  | 
  | referred to as DTMF, or  | |||||||||||||||||||||
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T  | 
  | This  | is  | controlled  | by including  | a  | P  | for  | Pulse  | or  | a  | T  | for  | 
  | Tone  | in  | the  | |||||||||||
  | 
  | dialing  | command,  | right  | before  | the  | digits  | you  | wish  | to  | 
  | have  | 
  | dialed  | ||||||||||||||
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  | in that manner.  | 
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  | For  | 
  | example,  | you  | would  | the  | number  | 
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  | by  | |||||||||||||||||
  | 
  | entering  | 
  | ATDP5551212 | 
  | and  | hitting | Return. | 
  | You | could | 
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 | |||||||||||||||
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  | the same number by entering ATDT5551212 and hitting Return.  | 
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  | If neither Pulse or Tone dialing is specified in the dialing com  | 
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  | mand,  | the  | command  | |||||||||||||||||||
modem will use whatever method was last  | 
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  | used. If the modem was reset or just powered up, it will use Pulse  | |||||||||||||||||||||||||
  | 
  | dialing, even if you do not use the letter P in your dial command.  | 
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  | Nearly  | all  | telephone  | systems  | in  | the  | U.S.  | are  | now  | compatible  | 
  | with  | |||||||||||||||
  | 
  | tone  | dialing.  | Since  | that  | 
  | is  | the  | faster  | method,  | you  | will  | probably  | |||||||||||||||
  | 
  | choose the tone method for your dialing.  | 
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  | An  | 
  | example  | of  | combining  | pulse  | and  | tone  | dialing  | could  | 
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  | involve  | a  | |||||||||||||
  | 
  | PBX | system  | where  | 9  | had  | to  | be   | then  | 
  | the  | rest  | of  | |||||||||||||||
  | 
  | the number   | pausing  | for  | a  | second  | dial  | 
  | 
  | tone.  | 
  | The  | ||||||||||||||||
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  | number would be dialed by entering ATDP9,T5551212 and  | 
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  | 
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  | hitting  | Return. (The  | ||||||||||||||||||||
comma causes a pause, which we’ll explain  | 
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  | soon.)  | 
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Result Codes  | 
  | It  | may  | be  | desirable  | to disable the Result Codes  | (see  | V  | 
  | command)  | ||||||||||||||||||
Enabled or  | 
  | altogether  | 
  | in  | certain  | applications,  | such  | as  | 
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Disabled  | 
  | auto  | dialing.  | The  | Q  | command  | is  | used  | to  | do  | this,  | 
  | 
  | with  | 
  | ATQ1 | ||||||||||||
  | 
  | disabling  | 
  | the  | Result  | Code  | transmissions  | 
  | and  | ATQ0 | 
  | 
  | 
  | (or  | 
  | ATQ)  | ||||||||||||
 | 
  | enabling  | 
  | them.  | If  | you  | do  | not  | select  | either  | method,  | 
  | the  | factory  | ||||||||||||||
  | 
  | default setting will enable the Result Codes to be sent.  | 
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Forcing an  | 
  | To  | 
  | dial  | up another  | 
  | modem  | that  | is  | in  | Originate  | 
  | mode,  | 
  | your  | |||||||||||||
Answer  | 
  | modem  | must  | be in  | Answer  | mode  | to  | initiate  | 
  | the  | 
  | 
  | "handshaking"  | |||||||||||||||
Tone,  | 
  | and  | 
  | establishment  | of  | a  | connection.  | This  | is  | 
  | done  | 
  | automatically  | |||||||||||||||