O-CSI
Originating – CAMEL Subscription Information

CAMEL operation requires additional CSI (CAMEL Subscription Information) to be included as part of a mobile subscriber’s subscription information in the HLR. This will be forwarded to the appropriate VLR when the mobile attaches and moves around the network. There are two types of CSI these are O-CSI and T-CSI (Terminating – CAMEL Subscription Information). The later phases of CAMEL include many variations of CSI.