# What does the VARTA error `caller_id_not_on_trunk` mean?

The `from` number you asked to dial with is not one of the trunk's registered numbers.


**HTTP status:** `400`  ·  **Type:** `invalid_request_error`

## What it means

The `from` number you asked to dial with is not one of the trunk's registered numbers.

## What causes it

Raised when the requested caller id isn't in the trunk's registered `numbers` (`backend/app/services/telephony.py`), reached from `POST /v1/calls` with `dial: true`.

## What to do

Omit `from` to use the trunk's default number, or register the number on the trunk first.