# Trunk DIDs/DDIs Parameters

A DID (Direct Inward Dialing) number, also called a DDI (Direct Dialing In) number outside North America, is a virtual number that tells a trunk which route a call belongs to. The two terms mean the same thing.

The DID/DDI numbers assigned to a trunk can be moved into and out of Cloud Voice as a CSV (comma-separated values) file. Importing lets you add many entries at once instead of typing them one by one, and exporting gives you a backup or a starting template. This reference describes each column in that file so you can build an import correctly, or read an export with confidence.

Each row defines one DID/DDI number and, optionally, a label for it.

| Column | What it holds | Required | Rules | Default |
| --- | --- | --- | --- | --- |
| DID/DDI | A virtual number that tells the trunk which route a call belongs to. | Yes, when the trunk's Trunk Type is `register` or `did_based`. | 31 characters maximum. Accepted characters depend on the trunk type (see below). | N/A |
| DID/DDI Name | A friendly label for the DID/DDI, used to recognize which trunk route is carrying the call. | No | 127 characters maximum. | N/A |

:::tip
The `DID/DDI Name` column is optional, but filling it in is worth the effort. A clear label (for example, the department or location the number serves) makes the trunk and its call routing far easier to read later.
:::

## Accepted characters for DID/DDI

The set of characters you can use in the `DID/DDI` column changes with the trunk type. The trunk type is set on the trunk itself, so check it before you prepare the file:

- `register` or `did_based` trunks: digits, letters, and the characters `(` `)` `.` `-` `+` `*` `#`.
- `port_based` or `private_network` trunks: digits, letters, and the characters `[` `]` `*` `#` `(` `)` `.` `-` `+` `!`.

:::note
The `DID/DDI` value is only mandatory on `register` and `did_based` trunks. On `port_based` and `private_network` trunks it is optional. Match your entries to the trunk type before importing so the file passes validation.
:::

:::caution
A row is rejected during import if a value breaks the rules above: a `DID/DDI` longer than 31 characters, a `DID/DDI Name` longer than 127 characters, or any character that is not allowed for the trunk type. Fix the offending rows and import again.
:::