Skip to main content

​
Outbound Calling with SIP Endpoints (Zoiper)

This guide explains how to set up an XML application, create a SIP Endpoint, configure a softphone (like Zoiper), and make an outbound call using Vobiz.

​
Prerequisites

  • A Vobiz account.
  • A virtual phone number purchased in the Vobiz Console (this will be your Caller ID).
  • A softphone application installed (e.g., Zoiper5).
  • A webhook server capable of returning Vobiz XML (e.g., an ngrok tunnel or hosted server).

​
Step 1: Create an XML Application

To control what happens when a call is placed from your SIP Endpoint, you need an XML Application that provides instructions to the Vobiz Media Server.
  1. In the Vobiz Console, navigate to Applications and click Create Application.
  2. Fill out the form:
    • Application Name: Enter a friendly name (e.g., Outbound Webhook App).
    • Answer URL: Enter your webhook URL (e.g., https://occasionally-isoelastic-dorie.ngrok-free.dev).
      • Note: Ensure the method matches your server (GET or POST).
    • Hangup URL (Optional): Enter a URL to receive hangup events.
Create XML Application
  1. Click Create Application.
Create Vobiz Application for Zoiper
Attach Number to Application

​
Understanding the XML Structure

When you make an outbound call from a SIP Endpoint, Vobiz needs to know where to route the call and what Caller ID to display. This is done using the <Dial> verb. 
<?xml version="1.0" encoding="UTF-8"?>
<Response>
    <Dial callerId="+91XXXXXXXXXX">
        <Number>+91XXXXXXXXXX</Number>
    </Dial>
</Response>
  • <Response>: The required root element for all Vobiz XML instructions.
  • <Dial>: The verb used to connect the active caller (your SIP Endpoint) to a new destination.
  • callerId attribute: This dictates what phone number shows up on the recipient’s phone. This must be a phone number associated with your Vobiz account.
  • <Number>: The noun nested inside <Dial> that specifies the destination phone number you are trying to reach (usually dynamically grabbed from the SIP dialpad).

​
Example Webhook Payload

Here is a Python example that dynamically extracts the number you dial in Zoiper (passed by Vobiz in the To parameter) and responds with the correct XML structure to route the call. 
from http.server import BaseHTTPRequestHandler, HTTPServer
import urllib.parse

class RequestHandler(BaseHTTPRequestHandler):
    def handle_request(self):
        query = urllib.parse.urlparse(self.path).query
        params = urllib.parse.parse_qs(query)
        
        # Vobiz sends the dialed number in the 'To' parameter
        to_number = params.get('To', [''])[0]
        
        # Clean up SIP URI if present
        if 'sip:' in to_number:
            to_number = to_number.split('@')[0].replace('sip:', '')
            
        xml_response = f"""<?xml version="1.0" encoding="UTF-8"?>
<Response>
    <!-- Replace callerId with your purchased Vobiz Number -->
    <Dial callerId="+91XXXXXXXXXX">
        <Number>{to_number}</Number>
    </Dial>
</Response>"""

        self.send_response(200)
        self.send_header('Content-type', 'application/xml')
        self.end_headers()
        self.wfile.write(xml_response.encode('utf-8'))
        
    def do_GET(self):
        self.handle_request()
        
    def do_POST(self):
        self.handle_request()

if __name__ == '__main__':
    server = HTTPServer(('0.0.0.0', 8080), RequestHandler)
    server.serve_forever()

​
Step 2: Create a SIP Endpoint

A SIP Endpoint acts as a bridge between your softphone and the Vobiz network.
  1. Navigate to Endpoints in the Vobiz Console and click Create SIP Endpoint.
  2. Fill out the configuration:
    • Alias: A friendly name for the endpoint (e.g., My Zoiper Endpoint).
    • Username: A unique alphanumeric username (e.g., johndoe123).
    • Password: A secure password (lowercase letters and numbers only).
    • Application: Select the XML Application you created in Step 1 (e.g., Outbound Webhook App).
  3. Click Create Endpoint.
Create SIP Endpoint Make note of the generated SIP URI (e.g., johndoe123@registrar.vobiz.ai) and password.

​
Step 3: Configure Zoiper (Softphone)

Now, configure your softphone to connect to the Vobiz SIP Registrar.
  1. Open Zoiper.
  2. Go to Settings > Accounts and click Add Account.
  3. Select SIP as the account type.
  4. Enter the credentials you created in Step 2:
    • User / Username: Your SIP Username (e.g., piyush123). Note: Zoiper might append a long string to your username, this is normal.
    • Password: The password you set (e.g., password123).
Add Username and Password in Zoiper
Add Hostname in Zoiper
  • Domain / Outbound Proxy: registrar.vobiz.ai
  1. Click Register or Next. You should see a green checkmark indicating successful registration.

​
Step 4: Make an Outbound Call

  1. In Zoiper, open the dialpad.
  2. Dial the destination phone number (e.g., +91XXXXXXXXXX).
  3. Press the Call button.
Making a call in Zoiper

​
What Happens Next?

  1. Zoiper sends the call to registrar.vobiz.ai.
  2. Vobiz sees the call is from your SIP Endpoint and looks up the assigned Application.
  3. Vobiz makes an HTTP request to your webhook URL (https://occasionally-isoelastic-dorie.ngrok-free.dev) passing To=+91XXXXXXXXXX.
  4. Your server responds with the <Dial> XML.
  5. Vobiz initiates the outbound call to the destination network, masking it with your callerId.