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

# Telephony and SIP Trunking

> Configure your phone numbers and telephony services with Rounded

# Telephony and SIP Trunking

Rounded offers you several options to manage your inbound and outbound calls. Whether you want to use our integrated numbers or connect your own telephony services, we have the solution adapted to your needs.

## Available telephony options

### 1. Rounded Numbers (Recommended to get started)

The simplest solution to begin:

* Automatic configuration
* No technical configuration required
* Support included
* Transparent billing

### 2. SIP Trunk - Connect your numbers

Use your own phone numbers via SIP trunking:

* Keep your existing numbers
* Preferential rates from your operator
* Full control over infrastructure
* Integration with existing systems

[**→ Complete SIP Trunk Guide**](/documentation/telephony/sip-trunk)

## Supported SIP providers

We have tested and validated integration with these major providers. **Other SIP providers are also compatible** - these are just our documented examples:

<CardGroup cols={3}>
  <Card href="/documentation/telephony/twilio-setup">
    <img src="https://mintcdn.com/roundedtechnologies/lAfocITNnbTuXMOc/logo/twilio.png?fit=max&auto=format&n=lAfocITNnbTuXMOc&q=85&s=8b9e55256d8e6d8fd48a6867a3267b9a" alt="Twilio" width="30" data-path="logo/twilio.png" />Twilio

    The global leader in cloud communications. Simple interface and robust API.

    **Advantages:**

    * Excellent documentation
    * 24/7 worldwide support
    * Easy integration
  </Card>

  <Card href="/documentation/telephony/telnyx-setup">
    <img src="https://mintcdn.com/roundedtechnologies/lAfocITNnbTuXMOc/logo/telnyx.png?fit=max&auto=format&n=lAfocITNnbTuXMOc&q=85&s=3ae684e63a8551d1efabc38483d339a4" alt="Telnyx" width="30" data-path="logo/telnyx.png" />

    Telnyx

    Global private network with competitive rates. Ideal for high volumes.

    **Advantages:**

    * Very competitive rates
    * Quality private network
    * Modern API
  </Card>

  <Card href="/documentation/telephony/zadarma-setup">
    <img src="https://mintcdn.com/roundedtechnologies/lAfocITNnbTuXMOc/logo/zadarma.png?fit=max&auto=format&n=lAfocITNnbTuXMOc&q=85&s=c3de8013e5be5098df13bbd69c25c049" alt="Zadarma" width="30" data-path="logo/zadarma.png" /> Zadarma

    European SIP provider with competitive international rates and flexible configuration.

    **Advantages:**

    * Competitive international rates
    * IP and credential authentication
    * Multiple server locations
  </Card>
</CardGroup>

### Other SIP providers

**Any SIP provider that supports standard SIP trunking will work with Rounded.** The providers above are documented examples, but you can use:

* **Local telecom operators** in your country
* **Regional SIP providers**
* **Enterprise SIP services**
* **Cloud PBX providers** with SIP trunk capabilities
* **Any RFC 3261 compliant SIP service**

Need help with a different provider? [Contact our team](mailto:team@callrounded.com) for configuration assistance.

## Provider comparison

| Provider    | Ease of use | Pricing | Support | Recommended for |
| ----------- | ----------- | ------- | ------- | --------------- |
| **Twilio**  | ⭐⭐⭐⭐⭐       | ⭐⭐⭐     | ⭐⭐⭐⭐⭐   | Startups, SMBs  |
| **Telnyx**  | ⭐⭐⭐⭐        | ⭐⭐⭐⭐⭐   | ⭐⭐⭐⭐    | High volumes    |
| **Zadarma** | ⭐⭐⭐⭐        | ⭐⭐⭐⭐    | ⭐⭐⭐     | European market |

## Custom integrations

Using another SIP provider? **It will work!** Standard SIP trunking is universally compatible.

**Contact our technical team if you need help:**
📧 **[team@callrounded.com](mailto:team@callrounded.com)**

We can assist you with:

* Configuration guidance for any SIP provider
* Integrations with existing PBX systems
* Multi-tenant configurations
* Enterprise deployments
* Custom SIP trunk setups

## SIP Architecture

### Inbound call flow

```mermaid theme={null}
graph LR
    A[Caller] --> B[Your SIP provider]
    B --> C[sip.callrounded.com]
    C --> D[Rounded Agent]
    D --> E[Voice response]
```

### Outbound call flow

```mermaid theme={null}
graph LR
    A[Rounded Agent] --> B[sip.callrounded.com]
    B --> C[Your SIP provider]
    C --> D[Recipient]
```

## Technical configuration

### Rounded SIP origination URI

```
sip:sip.callrounded.com;transport=tcp
```

### Recommended parameters

* **Protocol**: TCP (recommended) or UDP
* **Codecs**: G.722, G.711A, G.711U
* **DTMF**: RFC 2833
* **Port**: 5060 (standard SIP)

## Security and compliance

### Encryption

* TLS 1.2+ for signaling
* SRTP for audio streams
* Authentication by IP or credentials

### Compliance

* GDPR compliant
* European hosting available
* Secure call logs

## Next steps

1. **Beginners**: Start with integrated Rounded numbers
2. **Advanced users**: Configure a SIP trunk with your preferred provider
3. **Enterprises**: Contact us for custom configuration

<Note>
  💡 **Tip**: You can mix both approaches - use Rounded numbers for testing, then migrate to your SIP trunk for production.
</Note>

## Support

Our team is here to support you:

* 📧 Technical support: [team@callrounded.com](mailto:team@callrounded.com)
* 📖 Complete documentation in this section
* 🎯 Configuration examples for each provider