Vivox: What causes VxNoAuthenticationStanzaReceived (5044) errors?

VxNoAuthenticationStanzaReceived (5044) errors are typically caused by an improperly generated VAT (Vivox Access Token).

Although VATs are similar to JWT (Java Web Tokens), they are not the same. The header in a VAT is an empty JSON object (for example, {}), which encodes to e30.

Note: Do not set the header to be {"alg":"HS256","typ":"JWT"}.

For more information, see the Access Token Developer Guide in the Vivox Developer Documentation.