This value indicates the time-slots used by the port for receiving. It uses 32 bits ( in 4 bytes octet string ) for E1 and low 24 bits for T1. each bit represents a time slot for receiving : time-slot 0 = bit 0 (LSB - most right bit in last byte), ... ... time-slot 31 = bit 31 (MSB - most left bit in first byte ). value '0' indicate unused time-slot and value '1' indicates used time-slot. note : time-slots '0' and '16' are used for signalling in E1 interface.