1. Rosenberg, J., et al.: IETF RFC 3261 SIP: Session Initiation Protocol (2002).
http://www.ietf.org/rfc/rfc3261.txt
2. Rosenberg, J.: IETF RFC 5390 Requirements for Management of Overload in the Session Initiation Protocol (2008).
https://tools.ietf.org/html/rfc5390
3. Hilt, V., Noel, E., Shen, C., Abdelal, A.: IETF RFC 6357 Design Considerations for Session Initiation Protocol (SIP) Overload, Control (2011).
https://tools.ietf.org/html/rfc6357
4. Gurbani, V., Hilt, V., Schulzrinne, H.: IETF RFC 7339 Session Initiation Protocol (SIP) Overload Control (LBOC) (2014).
https://tools.ietf.org/html/rfc7339
5. Noel, E., Williams, P.M.: IETF RFC 7415 Session Initiation Protocol (SIP) Rate Control (RBOC) (2015).
https://tools.ietf.org/html/rfc7415