A phone company (or a telecom operator) with millions of customers need to maintain that many “circuit descriptors” in some database. I'll call them circuit descriptor databases — cdd, but Verizon call them INVENTORIES.

In Verizon, a complete circuit descriptor is known as a DESIGN or a LINE RECORD, to be PARSEd.

Databases can be relational or non-relational. In Verizon, most if not all of these disparate databases (NSDB, iview, Virtual Inventory ..) are accessed through their FT (flow through?). An FT is the proxy sitting in front of a database. Any system to query the cdd must go through the FT, load the line record and parse it.

circuit descriptors are stored in different INVENTORIES according to regions/states and “services” such as FTTP, Layer-1…