> ## Documentation Index
> Fetch the complete documentation index at: https://www.vobiz.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

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

> Cloud calling routes phone calls over the internet using VoIP and SIP — no hardware, no PBX, elastic scaling. How cloud calling differs from traditional telephony, what a business gains by switching, and how to set up cloud calling with the Vobiz API.

*November 2026 · Vobiz Team*

**Cloud calling is phone calls delivered as a managed service over the internet — no PBX hardware, no physical lines, no telecom technician required.** A business can have phone numbers in multiple countries, make and receive calls from any device or app, scale to hundreds of concurrent channels in seconds, and pay only for what it uses. The cloud provider handles everything below the API — routing, carrier interconnects, redundancy, and compliance.

> [!NOTE]
>
> **Key takeaways**
>
> * Cloud calling = VoIP phone infrastructure delivered as a cloud service, accessed via API or SIP
> * No hardware: no PBX, no ISDN lines, no copper — just internet and a cloud provider account
> * Scales instantly from 1 to 1,000 concurrent calls; pay per minute, not per line
> * For India: Vobiz provides 10-digit, 140-series, and toll-free numbers with ₹0.45/min pricing
> * Powers AI voice agents, contact centers, business phone systems, and OTP services

## Cloud Calling vs Traditional Phone Systems

| Factor | Traditional PBX / ISDN | Cloud Calling |
| - | - | - |
| **Hardware** | On-premise PBX box, ISDN cards | None |
| **Line capacity** | Fixed (buy more lines = more cost) | Elastic — unlimited concurrent |
| **Number provisioning** | Days to weeks via carrier | Self-serve, instant |
| **Geographic reach** | Physical lines per location | Global from one account |
| **Disaster recovery** | Manual failover, slow | Automatic geo-redundancy |
| **Remote access** | Complex ISDN VPN setup | Internet + SIP = works anywhere |
| **Cost model** | High CapEx + monthly line rental | Pay-per-minute, no minimum |
| **Updates** | IT team, downtime required | Automatic, no downtime |
| **Call recording** | Separate hardware/software | Built-in cloud storage |
| **API access** | None | Full REST API |

## How Cloud Calling Works

```
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
```

**SIP signalling** handles call setup and teardown — the INVITE, 200 OK, BYE sequence that establishes and ends a call. **RTP (Real-time Transport Protocol)** carries the actual audio as UDP packets. The cloud provider bridges your SIP connection to the carrier network, handling the protocol translation and routing.

For AI voice agents using real-time audio streaming (not SIP), Vobiz provides a WebSocket bridge via the XML `<Stream>` verb — your server receives raw audio and can send synthesized audio back in real time.

## Cloud Calling Use Cases

**Business phone system**: Replace your PBX with cloud calling. Employees use a softphone app (or even their browser) to make and receive calls on the company number. No hardware in the office required.

**AI voice agent**: The AI platform connects to Vobiz via SIP. When a call arrives on your Vobiz number, Vobiz routes it to the AI agent. The AI handles the conversation. No human needed for routine calls.

**Customer support line**: Inbound cloud calling with IVR, queue management, and call recording. Agents access their softphone via browser from any location.

**Outbound calling campaign**: Vobiz Campaign Manager dials your contact list concurrently, plays a message or connects to an AI agent, logs outcomes via webhook.

**OTP / verification calls**: Trigger a call via API, have Vobiz read an OTP using text-to-speech, and your user receives a voice verification. See the [OTP call example](https://www.vobiz.ai/docs/examples/vobiz-otp-call-xml-python.md).

**Number masking**: Route calls between buyers and sellers (or drivers and customers) through a Vobiz number without exposing either party's real number. See [Number Masking](https://www.vobiz.ai/docs/solutions/number-masking.md).

**International presence**: Get local phone numbers in 130+ countries through Vobiz. Customers in Germany call a local German number; the call routes to your team in India — with no international charges for the customer.

## Setting Up Cloud Calling with Vobiz API

**Make an outbound call:**

```python theme={null}
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"}
```

**Handle an inbound call with XML:**

```python theme={null}
# 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")
```

**Receive call status webhooks:**

```python theme={null}
@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"}
```

## Cloud Calling Quality: What Affects Call Quality

**Internet connection**: 50–100 kbps per concurrent call. Use a wired connection for call center agents; ensure symmetric upload/download bandwidth.

**Jitter and packet loss**: Voice is sensitive to network jitter (variable delay). Keep jitter below 30ms and packet loss below 1% for good quality. Use QoS (Quality of Service) to prioritise voice traffic on your network.

**Codec**: G.711 (64 kbps, uncompressed) gives the best quality; G.729 (8 kbps, compressed) is for low-bandwidth situations. Vobiz supports both.

**Provider PoP location**: Calls route through the provider's nearest point of presence. Vobiz has Mumbai-based infrastructure for India calls, keeping carrier latency under 50ms.

**Jitter buffer**: Vobiz handles jitter buffering on the cloud side — smoothing out network irregularities before the audio reaches the caller.

## Cloud Calling for India: What's Different

**Number types**: India requires specific number series for different use cases:

* **10-digit mobile** (e.g., +91 98765 43210): Standard inbound/outbound
* **140-series**: B2C outbound commercial calls (TRAI mandate)
* **1800 toll-free**: Customer service lines
* **1860 / 1800 (mixed)**: Various business categories

**TRAI regulations**: Outbound commercial calls must use 140-series numbers, be DLT-registered, and honour NDNC/DND preferences. Vobiz handles NDNC filtering and 140-series provisioning. See [India calling compliance](https://www.vobiz.ai/docs/compliance/india/calling-regulations.md).

**GST billing**: Vobiz issues INR invoices with GST — eligible for input credit for businesses.

**Local PoP**: Mumbai infrastructure reduces latency for Indian calls, important for AI agent response times and call quality.

## Cloud Calling Pricing

Cloud calling is priced per minute — you pay for the actual call duration, not for reserved line capacity.

| Component | Vobiz (India) |
| - | - |
| Outbound to mobile | ₹0.45–0.60/min |
| Outbound to landline | ₹0.30–0.45/min |
| Inbound | ₹0.20–0.45/min |
| Phone number rental | ₹200–500/month |
| 140-series number | ₹300–600/month |
| Toll-free (1800) | ₹500–1,000/month |

No setup fee, no minimum commitment, no contract required. Add credit and start calling.

## Next Steps

* [Create a Vobiz account](https://console.vobiz.ai) — sign up and buy a number in minutes
* [Read the quickstart guide](https://www.vobiz.ai/docs/quick-start.md) — make your first cloud call with the API
* [Explore cloud telephony](https://www.vobiz.ai/docs/blogs/what-is-cloud-telephony.md) — the broader cloud telephony landscape
* [AI voice agent setup](https://www.vobiz.ai/docs/solutions/ai-voice-agent.md) — connect AI to your cloud calling infrastructure
* [SIP trunking concepts](https://www.vobiz.ai/docs/concepts/sip-trunking.md) — technical deep-dive into the protocol


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