---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/80104#article
headline: "80104: Phone Number Already In Service"
url: https://www.twilio.com/docs/api/errors/80104
inLanguage: en
dateModified: 2026-06-08T12:04:59.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 80104: Phone Number Already In Service

Log Level: WARNING

## Description

This warning occurs when you try to add a phone number to a Proxy Service, but that phone number is already associated with that same Service. In Proxy, phone numbers are attached directly to a Service and become part of that Service's phone number pool.

### Possible causes

* The phone number you submitted is already associated with the Proxy Service's phone number pool.
* Your application may have retried an earlier add request after the phone number was already added to the Service.
* You attempted to create another Proxy PhoneNumber resource for a number that already exists in the same Service.

### Possible solutions

* List the phone numbers for the Proxy Service to confirm whether the number is already present before sending another add request.
* If the phone number is already attached to the correct Service, reuse the existing configuration instead of creating it again.
* If you need to recreate the association, remove the phone number from the Proxy Service and then add it again.

#### Additional resources

* [Proxy PhoneNumber resource](/docs/proxy/api/phone-number)
* [Phone Number Management](/docs/proxy/understanding-phone-number-management)
* [Proxy API Overview](/docs/proxy/api)