NTM controls are designed to reduce nonmessage traffic and allow more call comple- tions. This results in higher customer satisfaction and increased revenues from the network. 2. Give Priority to Single Link Connections. In a network designed to automatically alternate route calls, the most efficient use of available trunks occurs when traffic loads are at or below normal engineered values. When the engineered traffic load is exceeded, more calls are alternate-routed and, therefore, must use more than one link to complete a call. During overload situations, the use of more than one link to complete a call occurs more often, and the possibility of a multilink call blocking other call attempts is greatly increased. Thus in some cases it becomes necessary to limit alternate routing to give first-routed traffic a reasonable chance to complete. Some NTM controls block a portion or all alternate-routed calls to give preference to first-routed traffic. 3. Use of Available Trunking. The network is normally engineered to accommodate average business day (ABD) busy-hour calling requirements. Focused overloads (e.g., due to storms, floods, civil disturbances) and holiday calling often result in greatly increased calling and drastic changes from the calling patterns for which the network is engineered. This aberration can also be caused by facility failures and switching system outages. In these cases, some trunk groups are greatly overloaded, while others may be virtually idle. NTM controls can be activated in many of these cases to use the temporary idle capacity in the network. These controls are known as reroutes. 4. Inhibit Switching Congestion. A switching system is engineered to handle the ex- pected number of attempts generated over its trunk groups with little or no service degradation. However, large numbers of ineffective attempts that exceed the engineered capacity of the switching system can result in switching congestion. It this switching congestion is not relieved, it not only affects potential messages withi