# Phone numbers

URL: /systems/communications/phone-numbers · Id: `capability:phone-numbers`

> Phone numbers give a Startup local, toll-free and mobile numbers, port existing ones, and register business messaging with carriers.

Phone numbers give a [Startup](/business/nouns/startup) local, toll-free and mobile numbers, port numbers it already owns, and register its texting and caller identity with carriers.

## Contract
| Clause | Terms |
| --- | --- |
| Starts | Creation, or a new [Role](/business/nouns/role) or [Persona](/business/nouns/persona) that needs a number. |
| [Registration](/business/nouns/registration) | The [Brand](/business/nouns/brand) and each texting campaign register under the [Company](/business/nouns/company)’s tax ID before the first message. |
| Caller identity | Outbound calls carry the highest attestation the number qualifies for. |
| Opt-in | Marketing calls and texts to mobile numbers wait for prior written [Consent](/business/nouns/consent) ([Phone](/systems/legal-and-corporate/floor/phone)). |
| While held | Own. Every number belongs to the Startup and moves with it. |
| Records | A number [Channel](/business/nouns/channel) for voice agents, texts and verification codes. |

## Verbs
| Verb | Object | Event |
| --- | --- | --- |
| [Channel.create](/business/nouns/channel/create) | [Channel](/business/nouns/channel) | `Channel.created` |

## Interfaces
- [API](/code/api/reference)
- [SDK](/code/sdk/reference)
- [CLI](/code/cli/reference)
- [MCP](/code/mcp/reference)

## Example
An AI receptionist for veterinary clinics provisions one local number per clinic, 14 in all. Each clinic’s texting campaign is registered before its first appointment reminder goes out.