Trunk Interface
Field
0 or 1 in each bit
1101 1111
If the trunk interface is E1, bit one and bits four through eight of the time slot-0 word that is in the frame that does not contain the frame alignment signal can be used by a telephone company for country-specific requirements. Set these bits to 0 or 1 in accordance with any telephone company requirements. Bits two and three are fixed at 1 and 0. The bit order is one, two,... eight.