What must a silent open line call be considered until proven otherwise?

A silent open line call must be considered a potential TTY call until proven otherwise because it may indicate that a person attempting to communicate cannot speak or is in a situation where discretion is necessary. TTY (teletypewriter) users may initiate calls while remaining silent, as they communicate through text.

In emergency communication practices, it is critical to assess all scenarios where a caller is unresponsive. The protocol of treating a silent open line as a potential TTY call allows dispatchers to remain vigilant and responsive, ensuring that any help can reach a person who may be in distress but unable to speak verbally. This precaution helps prevent the risks associated with overlooking a genuine emergency situation.

Considering other options: treating the call as a standard voice call might lead to overlooking crucial information. Classifying it as a prank call risks dismissing a serious situation, and regarding it as a non-emergency call could result in inadequate response when an emergency may actually be present.