---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/80601#article
headline: "80601: Phone Number Not Available"
url: https://www.twilio.com/docs/api/errors/80601
inLanguage: en
dateModified: 2026-06-08T12:04:59.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 80601: Phone Number Not Available

Log Level: WARNING

## Description

This warning appears when the Twilio phone number you are trying to use is not available for the requested Proxy operation. In Proxy, a Twilio number can belong to only one `Proxy Service` at a time, and any number you set as a participant's `ProxyIdentifier` must already be added to that service's phone number pool.

### Possible causes

* The Twilio number is already associated with another `Proxy Service`, so it cannot be used in a second Proxy number pool.
* You specified a participant `ProxyIdentifier`, but that number has not been added to the target `Proxy Service` phone number pool.
* The number is still being kept in a Proxy pool while existing participants drain, so it is not yet ready to be removed or reused somewhere else.

### Possible solutions

* Check whether the number is already attached to another `Proxy Service`. If it is, remove it from that service before you try to use it in a different Proxy service.
* If you want to assign a specific `ProxyIdentifier`, add that Twilio number to the same `Proxy Service` first by creating a Proxy `PhoneNumber` resource.
* If you are moving a number out of a pool, mark it as Reserved and wait until no active participants are using it before you remove or reassign it.
* If your application needs more available numbers for active sessions, add more Twilio numbers to the Proxy phone number pool and size the pool to match your session volume.

#### Additional resources

* [Phone Number resource for Proxy](/docs/proxy/api/phone-number)
* [Phone Number Management for Proxy](/docs/proxy/understanding-phone-number-management)
* [Reserved Phone Numbers](/docs/proxy/reserved-phone-numbers)