AT&T DS1/DMi/ISDN-PRI manual Dmi, Isdn

	ADMINISTRATION OPTIONS AND REQUIREMENTS — GENERIC 2	7-83
Field 6	Defines the trunk type of a specific trunk group. The ISDN-PRI facilities may be
	used to support several different trunk types. These may include both conventional
	trunk types as well as the ISDN-dynamic trunk type. An important point to
	remember is that the particular service application and the incoming digits are the

primary determining factors that control which trunk type is selected. Most service applications may be supported (over ISDN facilities) by either a conventional trunk type or ISDN-dynamic.

Table 7-9, Trunks Supporting Signaling Type 20, shows some permitted field entries that support signaling type 20.

NOTE: Trunk types not included in the categories listed in table 7-9 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.

TABLE 7-9.Trunks Supporting Signaling Type 20

Trunk	Trunk
Description	Type
2-way CCSA/APLT	12—15
CO	16, *17 (Note), 18—20
Data	100—107
DID	*30, *31
DMI	*108, *109
FX	21—25
ISDN	120
M/S TIE	70—78
Special	2, 5, 6, 50—58, 62, 65—47, 90—93
TIE	32—40, *41, *42, *43, 44, 45, *46, *47
WATS	26, *27, 28

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

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.

For an ISDN trunk group, a dynamic trunk type (120) can be assigned to the group. This trunk type allows the group to process calls with a different trunk type on a call by call (CBC) basis. For example, one incoming call over the group may expect station number digits (for example, a MEGACOM call), while the next call over the group may expect a network number (for example, an SDN call).