Yes. Zentrunk SIP URI can be used to make calls from any softphone. Create an account on your softphone (e.g. X-Lite). Then, uncheck “register with domain and receive calls” under the account preferences.
Here are two tutorials that walk you through how to configure your softphone and soft switch (e.g., FreeSWITCH or Asterisk) to work with your Zentrunk SIP endpoint.