What does "Failed to generate request (12)" mean upon registration in iOS app

Question

When trying an IAX account with the Zoiper iOS app I get this error message: "Failed to generate request (12)". What does this indicate? The server is up and running and I would have expected a "Registration refused (29)" instead since the corresponding IAX2 user has not yet been configured on the server.

Answer 1

Zoiper just shows the error message returned from the server. So if there is a wrong message, most probably it is due to the configuration of the server.