Camel Subscription Information (CSI)
In another tutorial we have discussed about the camel protocol. Tutorial mentions introductory information about the camel subscription information(CSI) along with other protocol details. Here we will discuss in detail about the structure and components of the camel subscription information.
In CSI , subscription means, that a subscriber needs to have camel information in the subscriber profile on HLR or home location register. On SS7 level the information represents address of gsmSCF and other parameters. A mobile subscriber may have camel information for various camel services. Examples MO call, MT call, MO sms, MT sms and Data. Each service have its own type of camel information. There may be different types/values for each parameters. To make easy to understand, we will take the example of O-CSI or Originating Camel Subscription Information. O-CSI subscriber parameter is downloaded at gsmSSF during map protocol location update, if location update procedure gets successful, uon MO call , gsmSSF sends the triggers to the gsmSCF.
Camel Subscription Information(CSI) parameters
- Detection Points (DPs): A DP is like a state for an activity from the mobile device e.g dialing a number. When DP occurs, gsmSSF interrogates gsmSCF for further actions. In O-CSI, there can be two detection points (DPs), collected info and route select failure. First DP is triggered when user dials a number and other when there is call setup not possible.
- Service Key : A four byte integer value. Same gsmSCF may serve multiple services . For example key one for MO-Call and other for MT-Call.
- Default Call Handling: Parameter have two possible value , release or continue. When there is communication failure between gsnSSF and gsmSCF, default call handling is used. Mostly it is configured as release.
- gsmSCF address: This is the global title (Digits ) of gsmSCF.
On collect info DP , SSF sends the Camel IDP to the SCP. The IDP have called party sccp address as gsmSCF address and calling party address is the GT of gsmSSF. In IDP, there is service key along with other many call related parameters (eg calling number , called number etc.).