LICENSE_PLEASE_READ.txt

Contributions to the collaboration shall not be considered confidential.

Each contributor represents and warrants that it has the right and
authority to license copyright in its contributions to the collaboration

Each contributor agrees to license the copyright in the contributions
under the Modified (2-clause or 3-clause) BSD License or the Clear BSD License

Skype Limited hereby separately grants to the contributors a license
under its patents to the software contributed by Skype for internal
evaluation and testing purposes only. This license expressly excludes
use of the software for distribution or use in any commercial product or
any commercial or production use whatsoever.

See the IPR statement made to the IETF for details:
http://datatracker.ietf.org/ipr/1297/