title: Does all the database instances or services has same listener port in Oracle?
body: <p>I am trying to understand the oracle database environment in my office.</p>
  
  <p>In the Oracle SQL developer in my office, there are multiple connections with same port and host, but with different services.</p>
  
  <p><img src="https://i.stack.imgur.com/JezOs.jpg" alt="enter image description here"></p>
  
  <p><em>From oracle documentation, I have read this:</em></p>
  
  <blockquote>
    <p><strong><em>Port:</strong> This is the listener port for the database. The default port for Oracle Database is 1521.
    <strong>Service name:</strong> This is the network service name of the database. Select either SID or Service name.</em></p>
  </blockquote>
  
  <p>Does it mean that the services/database instance runs on different ports but have a common listener port to external connections? </p>