Multi-Tech Systems ISI5634PCI/4/8 manual Registers

Chapter 4—AT Commands, S-Registers, Result Codes

Dual Tone Multi-frequency (DTMF) was a technique proposed by the phone company to replace “pulse dialing” to make dialing faster and more reliable. In anticipation to adding other “customer services”, 6 additional digits were included, totaling 16 digits. Most commercial phones only include 12 digits. Many specialized phones and telephone equipment (such as ADSI phones, PBXes, etc.) utilize all 16 digits. DTMF was first introduced in the 1960s to the general public as “touch tone” dialing. The conversion from “pulse dialing” to “touch tone” dialing took over 20 years in the US. To this date (and in the foreseeable future) all phone companies support pulse dialing, and most phones you buy still allow you to switch to pulse. In the 80s, DTMF found a complete new use as a “key pad” for voice mail and interactive voice response systems. Since these systems have become a way of life now, DTMF has become the most common “man machine” interface.

S-Registers

Certain modem values, or parameters, are stored in memory locations called S-registers. Use the S command to read or to alter the contents of S-registers (see previous section).

REGISTER UNIT		RANGE	DEFAULT	DESCRIPTION
S0	1 ring	0,1–255	1	Sets number of rings until the modem
				answers. ATS0=0 disables autoanswer
				completely.
S1	1 ring	0–255	0	Counts the rings that have occurred.
S2	decimal	0–127	43(+)	Sets ASCII code for the escape
		128–255		sequence character. Values greater than
				127 disable escape.
S3	decimal	0–127	13(^M)	Sets ASCII code for the carriage return
				character.
S4	decimal	0–127	10(^J)	Sets ASCII code for the line feed
				character.

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