---
page_type: error
code: 50425
message: >-
  50425: Participant and proxy address pairs for one or more participants
  already in use.
level: ERROR
product: Conversations
---

## Description

One or more of the requested participant and proxy address pairs are already registered in the system.

### Possible Causes

You are attempting to map a non-Chat (e.g. SMS) conversation participants with participant address and proxy address that are already assigned to an active conversation. There may be only one unique mapping between your conversation participant's public phone number and internal (proxying) Twilio phone number, in order to route inbound messages correctly.

### Possible Solutions

[Locate](/docs/conversations/api/conversation-resource#read-multiple-conversation-resources) a conflicting active conversation that has an identical participant added to it. To use such participant in the new conversation either [delete](/docs/conversations/api/conversation-resource#delete-a-conversation-resource) old conversations completely if you don't need the message history, or just remove the participant that uses these numbers in a previous conversation.