# SIP Trunking Overview

SIP trunking on Cloud Voice connects your own PBX, SBC, or other SIP equipment to the public phone network. You create trunks in the [dashboard](https://voice.izt.cloud), point your phone numbers at them for inbound calls, and place outbound calls through them with validated caller ID and STIR/SHAKEN signing. Everything on this page links into a deeper guide.

## Trunk types

Cloud Voice supports three trunk types, distinguished by how they authenticate:

| Type | Authentication | Best for |
| --- | --- | --- |
| **Register** | SIP registration with auto-generated username and password | PBXs behind NAT or on dynamic IP addresses |
| **IP** | An allowlist of your IP addresses (CIDR notation) | Equipment with static public IPs |
| **IP + Trunk Group** | IP allowlist plus a trunk-group identifier | Multiple trunks sharing the same IP range |

See [Trunk Authentication](/sip/trunks/authentication/) for how each type works and when to choose which, and [Create & Manage Trunks](/sip/trunks/create/) for the step-by-step setup.

## Inbound: phone numbers (DIDs)

Each phone number on your account carries its own inbound routing. A number can:

- route to one of your **trunks**,
- route directly to a **SIP URI** or a **domain**,
- **forward** to another phone number, or
- stay **outbound-only** (inbound calls are rejected).

Details and when-to-use guidance are in [Inbound Number Routing](/sip/routing/inbound/).

## Outbound: caller ID and signing

Outbound calls through a trunk are validated before they reach the phone network:

- The caller ID you present must be a number authorized on the trunk, unauthorized caller IDs are overridden, never passed through. See [Outbound Calling & Caller ID](/sip/routing/outbound/).
- International destinations are controlled per trunk with country-code allow and block lists.
- Calls are signed with [STIR/SHAKEN](/sip/stir-shaken/) attestation so they present trustworthy caller ID downstream.

## Visibility and troubleshooting

Every call produces a call detail record, and each trunk exposes live registration status and call statistics, see [CDRs & Call Troubleshooting](/sip/cdrs/). You can also receive push notifications for registration, call, and fax events via [Webhooks & Events](/sip/webhooks/).

## Beyond the basics

- [Faxing over SIP](/sip/fax/), send and receive faxes on Cloud Voice.
- [API Reference](/sip/api/), programmatic access to trunks, stats, and fax.

:::tip[New to Cloud Voice?]
The fastest path: sign in at [voice.izt.cloud](https://voice.izt.cloud), create a trunk under **Infrastructure → Trunks**, then assign a number to it from the **Numbers** page. The dashboard includes an interactive "Set Up a SIP Trunk" guide that walks you through it live.
:::