When is it necessary to perform a Trace Procedure for an incoming 911 call?

Performing a Trace Procedure for an incoming 911 call is essential in situations where there is no Automatic Number Identification (ANI) or Automatic Location Identification (ALI) available. ANI and ALI are vital tools that allow emergency services to quickly ascertain the identity and location of the caller. When these systems fail or are not functioning for a particular call, it becomes imperative to initiate a Trace Procedure. This process aids in determining the origin of the call, especially crucial in emergencies where the caller may be unable to provide their information, or the call may be malicious or intentionally misleading.

The other scenarios listed would not necessitate the execution of a Trace Procedure since they either provide the necessary caller information or are not situationally critical. For instance, if ANI/ALI is available, the need for tracing is mitigated, as the information is already at hand. Similarly, limiting the need for a trace solely to emergency situations overlooks other instances where a trace could be necessary, like non-emergency calls where the caller's information remains unknown. Lastly, valid numbers being unknown does not by itself trigger a trace unless the ANI/ALI is also non-existent. Thus, the correct choice underscores the importance of taking action when basic identifying information is not available to safeguard the