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

# SIP Integration Issues

> Troubleshoot SIP trunk connection problems and configuration issues

<Warning>
  **Done for you — any region, any country (our EU partner carrier)**

  If you prefer not to configure a SIP trunk or import numbers yourself, our **EU partner carrier** can supply **local numbers in any region and any country**, set up the **SIP trunk**, and **import the connection into Famulor** for you. Provisioning runs **end-to-end through the partner** (carrier-side), so you skip DIY trunk and number import in Famulor.

  * **Custom number region / full-service onboarding:** [Famulor Custom Number Region form](https://tally.so/r/w4bN2Y)
  * **More detail or bespoke options:** [support@famulor.de](mailto:support@famulor.de)
</Warning>

> Troubleshoot SIP trunk connection problems and configuration issues

This guide helps resolve common SIP integration issues when connecting your SIP provider to Famulor.

## Testing Strategy

1. **Test outbound calls first** – easier to configure
2. **Test inbound calls second** – after outbound works

## Outbound SIP Issues

### Connection Problems

**SIP trunk not connecting for outbound calls:**

1. **Verify SIP credentials** – username, password, server details
2. **Phone type selection** – check with provider for correct type
3. **Fixed IP configuration** – usually enable and enter provider's IP address
4. **Provider settings** – verify codec, transport, port settings

### SIP Registration Issues

**Important:** Famulor platform:

* **Does NOT send SIP REGISTER** messages to your provider
* **Does NOT require receiving SIP REGISTER** from your provider
* Uses **direct call authentication** instead

### Testing Outbound

1. Configure SIP trunk settings
2. **Make a direct test call** through the platform
3. Check call logs for errors

## Inbound SIP Issues

### Authentication Setup

**For inbound calls:**

1. **Use IP authentication** – instead of username/password
2. **Whitelist provider IPs** – add ALL provider IPs in our platform
3. **Provider configuration – IMPORTANT**
   * **Use our FQDN domain** for routing (NOT the outbound IP)
   * **Send to domain** – ensures correct routing
   * **Do NOT send to IP** – causes routing issues

### Common Inbound Issues

**Calls not reaching assistant:**

* Verify all provider IPs whitelisted
* Ensure provider sends to FQDN domain (not IP)
* Check destination number format

## General Issues

**Network problems:**

* Check internet connectivity
* Verify no firewall blocking SIP traffic

**Provider compatibility:**

* Verify provider supports direct calling (no registration)
* Check IP authentication support

## Testing Checklist

### Before Contacting Support

1. **Outbound test:**
   * [ ] Credentials verified
   * [ ] Phone type selected correctly
   * [ ] Fixed IP enabled with provider's IP address
   * [ ] Direct test call attempted

2. **Inbound test:**
   * [ ] IP authentication configured
   * [ ] All provider IPs whitelisted in our platform
   * [ ] Provider configured to send to FQDN domain (not direct IP)
   * [ ] Test call from external number

3. **General:**
   * [ ] Network connectivity verified

## FAQ

### Transfer Phone Call Not Working

**Q: Why is the Transfer Phone Call function not working?**

**A:** If call transfers are failing, try these solutions:

1. **Check SIP transfer settings:**
   * Set transfer call to "Advanced" mode
   * Use SIP URI format: `sip:number@sip-server`
   * Example: `sip:+1234567890@sip.provider.com:5060`

2. **Verify provider support:**
   * Confirm your SIP provider supports SIP REFER
   * Check if transfer functionality is enabled on your account
   * Some providers require specific configuration for transfers

3. **Test different formats:**
   * Try with port: `sip:+1234567890@sip-server:5060`
   * Try without port: `sip:+1234567890@sip-server`
   * Try simple format: `sip:+1234567890`

4. **Verify destination:**
   * Ensure the target number is reachable
   * Test if the number answers calls normally
   * Check if the number is blocked or restricted

5. **Common issues:**
   * Provider doesn't support SIP REFER
   * Incorrect SIP URI format
   * Network/firewall blocking transfer requests
   * Destination number not answering

**Troubleshooting steps:**

1. Test with a known working number first
2. Try different SIP URI formats
3. Contact your SIP provider to confirm transfer support
4. Check call logs for specific error messages

## Getting Help

**When contacting support, provide:**

* Error messages from call logs
* SIP trunk configuration
* Test results (outbound and inbound)
* Transfer attempt details and SIP URI format used

## Related Docs

* [SIP Integration Setup](/en/provisioning/sip-ai/sip-integration)
* [SIP Troubleshooting](/en/provisioning/sip-ai/sip-troubleshooting)
* [Support](/en/support)