Two data modes

Data can be downloaded to an ADSI telephone in one of two modes:

Server display control (SDC)
Server display control mode is used when an IVR voice application uses a continuing connection between the generating device (such as Blueworx Voice Response) and the ADSI telephone. Use this mode for downloading data that is specific to the user; for example, information about the user's bank account.
Feature download management (FDM)
Feature download management mode allows a number of alternative display and key setups (known as overlays) to be downloaded and stored in the ADSI telephone. These overlays can be selected by various signals (or events) that occur at the telephone. The overlays remain active on the telephone after the telephone call that downloads them has been completed.