3Com ISDN Modem manual Registers except S0 are the 3Com extended registers

B-4 APPENDIX B: AT COMMANDS, S REGISTERS, AND RESULT CODES

S Registers

Table B-2 provides a complete list and descriptions of the S registers supported by the 3C882 ISDN modem. All

S registers except S0 are the 3Com extended registers.

S registers notated with an asterisk are stored in nonvolatile memory and will not be cleared or returned to the default value if the ISDN modem is powered down.

Table B-2 S Registers

Registers	Descriptions
S0	Auto Answer:
	0	— Disabled (default)
	X— Number of rings before auto answer (1-255).
S50*	ISDN Switch Signaling Type:
	0	— Unknown (default)
	1	— AT&T 5ESS Custom
	3	— NI1/AT&T 5ESS
	6	— NI1/NTI DMS 100 or Siemens EWSD
S51*	Phone #1
S52*	Phone #1 Service Profile ID (SPID)
S53*	Phone #2 (if required by your carrier)
S54*	Phone #2 Service Profile ID (SPID) (if required by your carrier)
S55	Terminal Endpoint Identifier 1:
	Stores the first TEI assigned by the switch. A value of 255 indicates no TEI
	has been assigned. This field is read-only.
S56	Terminal Endpoint Identifier 2:
	Stores the second TEI assigned by the switch if a second directory number is
	required by your carrier. A value of 255 indicates no TEI has been assigned.
	This field is read-only.
S57	Terminal Initialization State:
	Indicates the status of the first TEI using SPID 1. This field is read-only.
	0	— ISDN modem has not attempted initialization
	1	— ISDN modem has initialized successfully using SPID 1
	2	— ISDN modem has failed initialization using SPID 1