In North America, Telcordia SR-3511 (originally known as TA-1129+)[3] and GR-1129-CORE protocols serve to link switches with the IN systems such as Service Control Points (SCPs) or Service Nodes.[4] SR-3511 details a TCP/IP-based protocol which directly connects the SCP and Service Node.[3] GR-1129-CORE provides generic requirements for an ISDN-based protocol which connects the SCP to the Service Node via the SSP.[4]