0x0C Logical Span

Byte | AIB Field Description
--- | ---
2 | Address Element: 0x0C
3 | Data Length: 0x02
4, 5 | Data[0, 1] Logical Span ID (MSB, LSB)

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.
Range of channels provided by T1 or E1 transmission service. A physical span is a group of channels taking up a single physical wire. A logical span is a group of channels taking up less than a single logical wire, or carried over more than one physical wire.
Most Significant Bit
Least Significant Bit