# 50408: Invalid participant proxy address

Log Level: ERROR

## Description

An invalid participant proxy address was supplied.

### Possible causes

* Participant MessagingBinding.ProxyAddress parameter provided with the request is not a valid conversation proxy address.

### Possible solutions

* Check that the length of MessagingBinding.ProxyAddress parameter does not exceed 256 characters.
* Ensure that MessagingBinding.ProxyAddress parameter contains an address with valid syntax (e.g. SMS phone numbers must follow [E.164 format](/docs/glossary/what-e164)).