> ## Documentation Index
> Fetch the complete documentation index at: https://docs.get2dial.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Registration failures

> Diagnose why a registration-trunk carrier or a SIP device won't register or authenticate with Get2Dial.

A carrier set up as a **Registration trunk**, or a SIP device, fails to register or
authenticate.

## Quick checks

* Are you using a **Registration trunk**, or did you mean **IP trunk** (no registration,
  authenticated by IP instead)?
* Do **Auth username**, **Auth password**, and **Auth realm** exactly match what your
  carrier or device provider issued you?

## Cause: wrong trunk type for how your carrier authenticates

**How to check:** Confirm whether your carrier authenticates by IP address or by
username/password. Using **IP trunk** with a carrier that expects registration (or the
reverse) fails immediately.
**How to fix:** Set **Trunk type** to match — see
[Connect a SIP carrier](/voice/connect-a-carrier).

## Cause: authentication credentials are wrong

**How to check:** Re-check **Auth username**, **Auth password**, and **Auth realm**
character-for-character against what your carrier provided.
**How to fix:** Re-enter them. A password field left blank on an edit keeps the existing
stored password — if you're rotating a credential, you must re-type the new password, not
only the username.

## Cause: transport or port mismatch

**How to check:** Confirm **Transport** (UDP, TCP, or TLS) and **Remote port** match your
carrier's requirements exactly — UDP on port 5060 is the default, but not universal.
**How to fix:** Correct the transport or port.

## Cause: IP-based auth expected, but credentials were entered

**How to check:** If your carrier authenticates by IP allowlisting rather than
username/password, leave **Auth username** and **Auth password** blank.
**How to fix:** Clear those fields.

## If none of this worked

<Snippet file="support-ticket-contents.mdx" />