<p>Following some investigation, the difference in behaviour comes from the presence (or lack) of a pre-loaded Route header. This header points to a TLS interface, making opensips (while handling the preload route) to force a TLS send socket . According to <a href="https://github.com/OpenSIPS/opensips/issues/420" class="issue-link" title="Allow TCP without transport=tcp header">#420</a>, if no proto is dictated by RURI, the one from forced socket is used.</p>

<p style="font-size:small;-webkit-text-size-adjust:none;color:#666;">&mdash;<br>Reply to this email directly or <a href="https://github.com/OpenSIPS/opensips/issues/452#issuecomment-91317097">view it on GitHub</a>.<img alt="" height="1" src="https://github.com/notifications/beacon/AFOcia75akFEM_iE95xiFnOHlyDAVxrMks5n9roLgaJpZM4D70fU.gif" width="1" /></p>
<div itemscope itemtype="http://schema.org/EmailMessage">
  <div itemprop="action" itemscope itemtype="http://schema.org/ViewAction">
    <link itemprop="url" href="https://github.com/OpenSIPS/opensips/issues/452#issuecomment-91317097"></link>
    <meta itemprop="name" content="View Issue"></meta>
  </div>
  <meta itemprop="description" content="View this Issue on GitHub"></meta>
</div>