SDM is a database. It consists of following main features.

·         HLR (Home Location Register): HLR is a static database. 

·         AUC (Authentication  Centre):  Authenticate a subscriber into the network.

·         EIR  (Equipment  Identity  register):  An  EIR reduces  the  threats  of  theft  of  handsets  by enabling  individual  operators  to  prevent  the  use  of  stolen  handsets  in  their  own networks. This improves users’ security by switching off stolen phones, making them useless for mobile phone thieves and thus less likely to be stolen in the first place

·         MNP  (Mobile  Number  Portability):  MNP  enables  mobile  telephone  users  to  retain their mobile telephone numbers when changing from one mobile network operator to another.

Services that can be configured using a HLR

·         PRBT (Phone Ring Back Tone)

·         CAMEL (Customized Applications for Mobile Enhanced Logic): Can set triggers when a call is originated (CCSI) or when a location changes (MCSI)

·         ODB (Operator Determined Barring) : i.e. suspend a post-paid customer