---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/18018#article
headline: "18018: PO Box not allowed."
url: https://www.twilio.com/docs/api/errors/18018
inLanguage: en
dateModified: 2026-06-09T11:00:42.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 18018: PO Box not allowed.

Log Type: APPLICATION

Log Level: ERROR

## Description

This error occurs when you submit a PO Box for a phone number address requirement that must use a physical address. Twilio Address resources represent a physical location, and some phone numbers require a qualifying address for regulatory compliance before you can purchase or use the number.

### Possible causes

* You submitted a PO Box in the address information for a regulated phone number. A PO Box does not satisfy proof of address where a physical local address is required.
* The phone number requires a qualifying address, and the address on file does not match the required geography for that number. Depending on the number, Twilio may require an address in the number's country, outside the number's country, or within the locality or region covered by the number's prefix.
* The address mapped to the phone number did not pass validation or did not satisfy the regulatory requirement, so it could not be accepted or selected.

### Possible solutions

* Replace the PO Box with the end user's physical residence or place of business. Use a complete street address instead of a mailing-only address. ([help.twilio.com](https://help.twilio.com/articles/223182868))
* Review the number's address requirement before you buy or update the number. If the number requires `local`, provide an address in the phone number's country. If the regulation requires locality matching, use an address in the locality or region covered by the number's prefix. If the number requires `foreign`, use an address outside the phone number's country.
* Create or update the Address resource with the corrected physical address. Then map that address to the phone number in Console under Regulatory Information, or use the `AddressSid` parameter through the Incoming Phone Numbers API.
* If the address does not appear as a selectable option, create a new validated address in the correct format and locality, then try again. Twilio might not show addresses that did not pass validation or do not satisfy the regulatory requirement.

#### Additional resources

* [Addresses API](/docs/usage/api/address)
* [Phone Number Regulatory Compliance getting started](/docs/phone-numbers/regulatory/getting-started)
* [How to map a regulatory address to an existing phone number](https://help.twilio.com/articles/31155205145243)