401 Unauthorized from IP Phone

Version 1
    This document was generated from CDN thread

    Created by: Ngoc Thong Chung on 04-04-2011 02:42:35 PM
    I am trying to send a simple message to a phone (CiscoIPPhoneText XML object) and it returns a 401 code. I am setting the Authorization HTTP header as recommended by the documentation:
    Authorization: Basic <Base64 string of username:password>
    The username password combination is from a user registered in the CM and can log in (he is admin).
    When using those credentials, I get a 401. I suspect that I use a user who cannot do that. That user is member of every group available in the CM.
    If this information can help, one of the HTTP response headers is:
    WWW-Authenticate: Basic realm="<ip phone id>"
    Also, the phone model is 7960 and the CM version is 8.5.
    Thank you