Digi 90000583_A manual At+Ms

AT	Function	Result
Command		Code
	Operating Mode
	This command controls the preferred error correcting mode to be negotiated
	in a subsequent data connection.
	\N0 Selects normal speed buffered mode	OK n=0 to 5
AT\Nn	\N1 Serial interface selected - Selects direct mode
		ERROR
	\N2 Accepted but ignored.	Otherwise
	\N3 Accepted but ignored.
	\N4 Accepted but ignored.
	\N5 Accepted but ignored.
AT\Vn	Accepted but ignored.	OK n=0 or 1
		ERROR
		Otherwise
AT+MS	Accepted but ignored.	OK
AT+MI	Accepted but ignored.	OK
AT%Cn	Accepted but ignored.	OK n=0 to 3
		ERROR
		Otherwise

Chapter 7 Special Features: Modem Emulation 51