What Is Cloud Calling? How Cloud Phone Calls Work for Business

Your app / PBX / AI agent
         ↕  SIP (Session Initiation Protocol)
         ↕  WebSocket (for AI agents)
Cloud Calling Provider (Vobiz)
         ↕  Carrier interconnects
Mobile / landline networks (PSTN)
         ↕
Called party's phone rings

import requests

response = requests.post(
    "https://api.vobiz.ai/v1/calls",
    headers={"X-Auth-Token": "YOUR_AUTH_TOKEN"},
    json={
        "from": "+911234567890",
        "to": "+919876543210",
        "answerUrl": "https://your-server.com/handle-call",
        "answerMethod": "POST"
    }
)
print(response.json())  # {"call_uuid": "abc-123", "status": "queued"}

# When Vobiz receives a call, it POSTs to your answerUrl
# Return XML to control the call

from fastapi import FastAPI
from fastapi.responses import Response

app = FastAPI()

@app.post("/handle-call")
async def handle_call():
    xml = """<?xml version="1.0" encoding="UTF-8"?>
<Response>
    <Speak>Welcome to Acme Corp. How can we help you today?</Speak>
    <Dial><Number>+919988776655</Number></Dial>
</Response>"""
    return Response(content=xml, media_type="application/xml")

@app.post("/call-status")
async def call_status(request: Request):
    data = await request.json()
    # data contains: CallUUID, CallStatus, Duration, From, To
    print(f"Call {data['CallUUID']} ended: {data['CallStatus']}, {data['Duration']}s")
    return {"status": "ok"}