Hn - Control The Switchhook

Command Line Format
AT [cmds] H [suffix] [cmds] <CR>

Suffix Values
0 through 1

Default
N/A

Stored by &Wn
N/A

Displayed by &V
N/A

Description
The H command controls the line relay, and it can cause a transition to the hangup process.

H0 instructs the modem to execute the hangup process if it is in one of following:

1. Online Command State,

2. Local Analog Loopback Self-test State

3. Online Command Substate of the Local Analog Loopback Process.

If the modem is online and data transfer is still pending, then the modem stays connected for the time set by S38 in an attempt to complete the transfer of these data. If the data is sent before the time limit, the modem hangs up and returns the OK result code. If the data is not sent before the time limit, the modem hangs up and returns a NO CARRIER result code. See S38.

H1 instructs the modem to go off-hook, but does not cause execution of the Handshaking Process. If the modem is already in the Online Command State, then H1 has no effect.

H2 causes operation of the line relay but not the phone relay. This feature is used in some 1200 bits/s modems.

Execution Time H0 - Depends on the modulation in use. 500 ms maximum, in async and sync modes that do not use echo cancellation. The execution is 4 seconds if modulation uses echo cancellation. The time is determined by S38 (def=20s) in buffered modes.
H1 p; 10 ms maximum

DTE Interface Lines Affected
DSR, RL, SD, HS

LEDs Affected
CD, HS, MR, OH

Cross Reference
Commands - &Ln - Line Type Selection (Dialup/Leased) , Mn - Select Speaker Function Option , &Dn, &Jn - Jack Type Selection (Auxiliary Relay Options) , &Tn

Line signals - Carrier, Ringing voltage

Relays - Auxiliary, Line

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