; example:
; Warning: 301 isi.edu "Incompatible network address type 'E.164'"
; 300 Incompatible network protocol:
; One or more network protocols contained in the session description are not available.
; 301 Incompatible network address formats:
; One or more network address formats contained in the session description are not available.
; 302 Incompatible transport protocol:
; One or more transport protocols described in the session description are not available.
; 303 Incompatible bandwidth units:
; One or more bandwidth measurement units contained in the session description were not understood.
; 304 Media type not available:
; One or more media types contained in the session description are not available.
; 305 Incompatible media format:
; One or more media formats contained in the session description are not available.
; 306 Attribute not understood:
; One or more of the media attributes in the session description are not supported.
; 307 Session description parameter not understood:
; A parameter other than those listed above was not understood.
; 308 Incompatible language specification:
; Requested languages not supported. Supported languages are [list of supported languages]; supported media are: [list of supported media].
; [RFC 8373]
; 330 Multicast not available:
; The site where the user is located does not support multicast.
; 331 Unicast not available:
; The site where the user is located does not support unicast communication (usually due to the presence of a firewall).
; 370 Insufficient bandwidth:
; The bandwidth specified in the session description or defined by the media exceeds that known to be available.
; 380 SIPS Not Allowed:
; The bandwidth specified in the session description or defined by the media exceeds that known to be available.
; [RFC 5630]
; 381 SIPS Required:
; The UAS or proxy cannot process the request because the SIPS scheme is required.
; [RFC 5630]
; 399 Miscellaneous warning:
; The warning text can include arbitrary information to be presented to a human user or logged. A system receiving this warning MUST NOT take any automated action.