---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/80402#article
headline: "80402: Identifier Proxy Pair Invalid"
url: https://www.twilio.com/docs/api/errors/80402
inLanguage: en
dateModified: 2026-06-08T12:04:59.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 80402: Identifier Proxy Pair Invalid

Log Level: WARNING

## Description

This warning indicates that Proxy could not accept the requested `identifier` and `proxyIdentifier` combination. Proxy uses the participant's Identifier and assigned Proxy Identifier to route calls and messages, and the same participant cannot be assigned the same Proxy number in concurrent active Sessions. If you provide a `proxyIdentifier` when you create a Participant, that Twilio number must already be in the Service's Proxy number pool.

### Possible causes

* You tried to use the same participant in more than one active Session with the same `proxyIdentifier`. Proxy requires a unique Proxy number for a participant in each concurrent active Session to avoid routing calls or messages to the wrong recipient.
* You sent multiple Participant create requests for the same `identifier` at the same time or very close together. That can create a conflicting Identifier and Proxy Identifier pairing across Sessions.
* Your Service does not have enough Proxy numbers for the number of overlapping Sessions your participants need to handle. A single participant cannot reuse the same Proxy number across concurrent active Sessions.
* You manually set `proxyIdentifier` instead of letting Proxy choose a number, and the requested pairing could not be used safely for the Session.

### Possible solutions

* Omit `proxyIdentifier` when you create the Participant and let Proxy select an available number from the Service pool.
* Add more Twilio numbers to the Proxy Service so each participant can receive a unique Proxy number for every concurrent active Session they join.
* Send requests sequentially when you need to add the same person to multiple Sessions. This helps prevent simultaneous assignment conflicts.
* Include `FailOnParticipantConflict=True` in Participant create requests, or in Session create requests that include participant parameters, so Proxy rejects conflicting requests before they create an ambiguous pairing.

#### Additional resources

* [Participant resource](/docs/proxy/api/participant)
* [How many Phone Numbers do I need?](/docs/proxy/phone-numbers-needed)
* [Phone Number Management](/docs/proxy/understanding-phone-number-management)