Actiontec electronic IS560LH user manual Communication Standard Setting, Carrier Control

Bn			Communication Standard Setting
This command determines CCITT vs. Bell standard.
		Command		Effect
		B0		Selects CCITT V.22 mode when the modem is at 1200
				bits/s.
		B1		Selects Bell 212A when the modem is at 1200 bits/s
				(default).
		B2		Unselects V23 reverse channel (same as B3).
		B3		Unselects V23 reverse channel (same as B2).
		B15		Selects V.21 when the modem is at 300 bits/s.
		B16		Selects Bell 103J when the modem is at 300 bits/s
				(default).
Result Codes:
	OK		n = 0, 1, 15, 16
	ERROR		Otherwise
Cn			Carrier Control

The modem will accept the C1 command without error in order to ensure backward compatibility with communications software that issues the C1 command. However, this modem does not support the C0 command. The C0 command may instruct some other modems to not send carrier (i.e., it puts them in a receive-only mode).

Command	Effect
C0	Transmit carrier always off.
C1	Normal transmit carrier switching.

Result Codes:

OK n = 1

ERROR Otherwise

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