[Asterisk-Dev] Why Proxy-Authenticate instead of WWW-Authenticate in chan_sip?

[Mikael Magnusson]

Hi,

It's often mentioned on the list that Asterisk is an user SIP agent and not a 
proxy. But why is then Proxy-Authenticate (and 407 Proxy
Authentication Required) used instead of WWW-Authenticate
(and 401 Unauthorized) in chan_sip. According to section 22.1 Framework
in RFC 3261:

  In SIP, a UAS uses the 401 (Unauthorized) response to challenge the
  identity of a UAC.

Regards,
Mikael Magnusson