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

# Custom SIP trunk setup

> Connect a carrier- or PBX-managed SIP trunk to Klatt, then verify inbound or outbound calling before accepting real traffic.

Connect a carrier- or PBX-managed SIP trunk to Klatt, then verify inbound or outbound calling before accepting real traffic.

## Prerequisites

* Access to the Klatt Console and **Telephony Configurations**.
* A carrier or PBX SIP address, call direction, and routing details.
* A workflow that is ready to answer or place a call.

## Configure a custom SIP trunk

1. Open **Telephony Configurations** and choose **Add telephony configuration**.
2. Select **SIP trunk** and choose **Inbound**, **Outbound**, or **Both** for the direction.
3. Enter the **Provider SIP address** and, for outbound calling, the **Destination country**.
4. Add the inbound or outbound authentication pair when the carrier requires it, then save the configuration.
5. Configure carrier routing and add or import the phone numbers used by the configuration.
6. Assign inbound numbers to workflows and place a controlled test call.

## Constraints and failure states

Outbound SIP requires a provider address and destination country. Authentication usernames and passwords must be supplied as matching pairs. A number without a workflow assignment cannot route the intended call experience, and the carrier must send traffic to the SIP address and numbers configured for the organization.

## Protect your data

Keep SIP credentials and carrier routing details in the protected configuration form. Do not place credentials, private trunk addresses, or real phone numbers in prompts or public examples.

## Related

* [Inbound telephony](/integrations/telephony/inbound)
* [Twilio](/integrations/telephony/twilio)
* [Call transfer tool](/voice-agent/tools/call-transfer)


## Related topics

- [Twilio setup](/integrations/telephony/twilio.md)
- [Inbound telephony](/integrations/telephony/inbound.md)
- [Call transfer tool](/voice-agent/tools/call-transfer.md)
- [End Call tool](/voice-agent/tools/end-call.md)
- [Webhook node](/voice-agent/webhook.md)