Go deep into the AT command (2)-Call Control Command

Go deep into the AT command (2)-Call Control Command

1 ATDDial Command dialing, ATD <str>, where <str> is the dialing string dialing character: 0 ~ 9. when an outbound call is initiated, if the call is established successfully, OK is returned. when the other party is on the machine, NO CARRIER is returned. If the operation is incorrect, + CME ERROR: <err> is returned; if a connection cannot be established (no sim card, NO network is found, or the network is disconnected), no carrier is returned.
2 ATAAnswer a call response. ATA responds to the call and calls are indicated by RING. If the connection is established successfully, OK is returned. If the connection fails to be established, NO CARRIER is returned.
3 ATH

Disconnect existing connection releases all existing connections. If all connections are released, OK is returned.

4 AT + VTS

DTMF and tone generation send DTMF audio. This command is only used for voice services. AT + VTS = <dtmf> set DTMF dialing. if the message is sent successfully, OK is returned. If the message is incorrect, + CME ERROR <err> is returned. <dtmf> is a single ASCII character. value Range: 0 ~ 9.

5 ATS0

Set the Automatic Answer function.
ATS0 returns the supported Automatic Answer wait time (seconds) range, for example: + S0 :( list of supported <n> s ).
ATS0? Returns the Current Automatic Answer time, for example, S0 = <n>.
ATS0 = <n> set the Automatic Answer time, and OK is returned correctly. If an ERROR occurs (the value of n exceeds the range), ERROR is returned. <n>: the waiting time (in seconds) for the Automatic answer, which is an integer between 0 and 59.

6 AT + CEER

Extended Error Report. This command shows the Cause of the call interruption when the call setting fails. For example: + CEER: "Cause Select: 67 Cause: 57"

7 ATDL

Redial the last phone number