AT&T DS1/DMi/ISDN-PRI manual Trunk Description Type, Did, Isdn TIE, Wats

ADMINISTRATION OPTIONS AND REQUIREMENTS — SYSTEM 85 7-25

Incoming ISDN dynamic trunk type 120 calls (to a System 85) may or may not specify an NSF. Generally, incoming calls from the public network will specify an NSF while calls from the private network will not specify an NSF. For example, if the NSF is delivered and it shows an SDN call, then the System 85 defaults to trunk type 46. For all other incoming NSF values, the switch will default to trunk type 30. For those incoming calls which do not deliver an NSF the switch will either use those interface endpoint trunks that are translated in procedure 116 or use a default that is dependent on the type call. For example, trunk type 41 is the default for switch-to- switch connections, trunk type 30 is the default for public network-to-switch connections, and trunk type 108 is the default for host-to-switch calls.

Table 7-2, Trunks Supporting Signaling Type 20, shows permitted field entries that support signaling type 20.

TABLE 7-2.Trunks Supporting Signaling Type 20

Trunk	Trunk
Description	Type
CO	16, *17 (Note 1), 18, 19, 20
Data	100—107
DID	*30, *31
DMI (Note 2)	*108, *109
FX	21—25
ISDN	120 (Note 3)
M/S TIE	70—78
Special	2, 5, 6, 50—58, 62, 65—67, 90—93
TIE	32—40, *41, *42, *43, 44, 45, *46, *47
WATS	26, *27, 28

NOTES:

1.Trunk types preceded with an asterisk (*) may be selected by trunk type 120 on an as needed Call-By-Call (CBC) Service Selection basis.

2.Trunk types not included in these categories may not be translated for ISDN-PRI service. Most conventional trunk types specify, as a part of their name, an in/out signaling sequence. Actually, these signaling sequences are disabled and type 20 signaling is used exclusively over ISDN facilities.

3.Beginning with the 1.0 software load of Generic 2 and the 1.2 software load of System 85 R2V4 digits may be inferred when using the ISDN-dynamic trunk type. The default of 30 infers DID (if necessary). A default of 46 infers AAR/ARS. (See Appendix C, Administrative Procedure Summary, for a complete explanation of this field.)

For ISDN trunk groups as well as other types of trunk groups, the entered type defines feature operation for the trunk group. For example, if a trunk group is assigned the type of 19, incoming calls over this trunk group are routed to the attendant console. On DID trunk type groups, the switch expects station number digits on all incoming trunks; on tie trunk type groups the switch can handle either station number digits or network numbers.