Telecom · Cerillion, source BSS, catalog, bill cycles
Cerillion BSS migration
Catalogs, accounts, and billing cycles moved onto Cerillion while the source stack stayed live. Parallel runs, then a rehearsed cutover. The first cycle on Cerillion was not the first time those invoices had been produced.
A UK operator
The constraint
The operator could not miss a bill run. Offers, account hierarchies, and cycle calendars lived on a source BSS that still had to collect until Cerillion was trusted. A weekend big-bang would have left no rollback anyone was willing to use. Mapping was the risk, not the install.
What we did
Coexistence first. Offers and accounts were mapped and frozen in a control file. Bill cycles ran in parallel on source and Cerillion against production-like volumes. Differences went to a reconciliation queue with owners, not a slide. Cutover was a MOP with a named rollback and the same engineers who built the map.
How it ran
Discovery and mapping, dress rehearsals, parallel bill runs, traffic redirect, hypercare. Source stayed available until two clean cycles on Cerillion. Hypercare was not a separate vendor.
What was true after
The operator billed on Cerillion without a missed cycle. Source was retired when finance signed the reconciliation, not when the project plan said go-live.