In case of using what communication channels a person does not have a reasonable expectation of privacy?
<p>In what scenario(s) a person doesn't have a <a href="https://en.wikipedia.org/wiki/Expectation_of_privacy" rel="nofollow noreferrer">reasonable expectation of privacy</a>?</p>

<ul>
<li>sending a traditional letter or parcel via the U.S. post </li>
<li>using work email account for sending private emails </li>
<li>making a cell phone call </li>
<li>listening to ones own cell phone's voicemail</li>
</ul>

<blockquote>
  <p><strong>Expectation of privacy</strong> is a legal test which is crucial in defining
  the scope of the applicability of the privacy protections of the
  Fourth Amendment to the United States Constitution.</p>
</blockquote>

<p>I presume you are addressing the various wiretapping laws. In all of those channels, one would have a reasonable expectation of privacy, in contrast to using CB radio or a megaphone. However the context of using the instrument affects that expectation, for example if your phone is on speaker you do not have a reasonable expectation that those around you cannot hear your conversation, when there are others around you. Also, there is no expectation of privacy surrounding employers monitoring employee emails for valid business purposes – but the federal government can't intercept your emails (without a warrant) just because you are using business email. The expectation of privacy is really about the surrounding circumstance, not the instrument you use.</p>

united-states privacy us-constitution