User Requirements for the Session Initiation Protocol (SIP) in Support of Deaf, Hard of Hearing and Speech-impaired Individuals. - Nathan Charlton; Mick Gasson; Guido Gybels; Mike Spanner; Arnoud van Wijk (RFC, 2002)

Transcoding Services Invocation in the Session Initiation Protocol (SIP) Using Third Party Call Control (3pcc). - Gonzalo Camarillo; Eric William Burger; Henning Schulzrinne; Arnoud van Wijk (RFC, 2005)

Framework for Real-Time Text over IP Using the Session Initiation Protocol (SIP). - Arnoud van Wijk; Guido Gybels (RFC, 2008)