| 摘要 |
<p>PURPOSE:To inform the busy state of a subscriber line without changing an existing interface by using a bit for controlling contention in the same interface in the basic access of an existing ISDN user network interface. CONSTITUTION:When it is desired to stop the delivery signal of a user by a subscriber line signal delivery circuit 3, the intention is informed from a buffer circuit 2 or the subscriber line signal delivery circuit 3 to a signal delivery prohibition circuit 4 by using control lines 10 and 11, respectively. The signal delivery prohibition circuit 4 receiving the information transfers a continuous logic value 0 to a signal delivery prohibition control line 8. To an AND circuit 5, the logic value 0 of an echo channel 7 is transferred as output not depending on the value of a signal delivery channel 6 on the user network interface since the signal delivery prohibition control line 8 is set at the logic value 0, and the user can recognize no transmission of the signal.</p> |
