UDC is a 3GPP initiative which seeks to rationalize the databases found across the key mobile technologies such as 2G, 3G, 4G, 5G and IMS. The general premise is that across these technologies, common subscriber data is routinely stored and accessed. As such, this data can be stored in a common backend database termed the UDR (Unified Data Repository). Entities seeking to obtain specific information from this common database can use AFEs (Application Front Ends) specific to their network. For example, a 4G MME wishing to access a specific piece of subscriber data will utilize the 4G HSS AFE.