0x3A D Channel Data Link Connection Identifier

Byte | AIB Field Description
--- | ---
2 | Address Element: 0x3A
3 | Data Length: 0x04
4 | Data[0] Slot of ISDN card
5 | Data[1] D-Channels Offset (0-31)
6 | Data[2] SAPI
7 | Data[3] TEI

See Address Information Block.
The information in an AIB that follows the header, down to the data field. An AIB can have one or more Address Elements. AEs correspond to Span, Channel, and SS7 Link.
See Integrated Services Digital Network.