The Integrated Services Digital Network (ISDN) Subaddress Encoding Type for tel URI. - Mayumi Munakata; Shida Schubert; Takumi Ohba (RFC, 2006)

Guidelines for Using the Privacy Mechanism for SIP. - Mayumi Munakata; Shida Schubert; Takumi Ohba (RFC, 2010)

User-Agent-Driven Privacy Mechanism for SIP. - Mayumi Munakata; Shida Schubert; Takumi Ohba (RFC, 2010)