British Telecom

The Challenge

Decades of British Telecom's business logic were encoded in procedural Mainframe code — deeply embedded into daily operations at national telecom scale, poorly documented by nature of the platform, and not something that could simply be lifted and shifted onto modern infrastructure. Migrating it to Oracle Data Integrator 12c meant genuinely re-architecting that logic, not just relocating it: procedural, line-by-line Mainframe code doesn't map directly onto ODI's declarative, dataset-driven integration model, so every piece of transformed logic had to be re-thought in terms of how ODI actually processes data. The migration needed a coherent target architecture capable of absorbing that transformed logic in a structurally sound way, rather than accumulating ad hoc transformations with no unifying design. File transfers that previously ran through Mainframe job scheduling needed an equivalent automation layer outside the Mainframe entirely. And because the migration ran across multiple environments over roughly two years, it needed disciplined repository management and release control — without it, a programme of this scale and duration would have drifted into inconsistency between environments long before reaching production.

Our Solution

As ODI Lead, GYSP spearheaded the migration of British Telecom's legacy Mainframe systems to a modern Oracle Data Integrator 12c architecture. The IRS2 architecture was designed as the structural foundation for the entire migration — the target model every piece of transformed Mainframe logic would be built against. Procedural Mainframe code was systematically transformed into optimised ODI datasets, re-architecting business logic from a sequential, line-by-line model into ODI's declarative, dataset-driven integration model while preserving the original business rules and making them maintainable and observable on a modern platform. File transfers previously handled through Mainframe job scheduling were automated via Unix shell scripting, replicating and improving on the reliability of the legacy job dependency chains. ODI agents were deployed and managed on Oracle WebLogic servers, providing the production runtime layer that executed the transformed integration logic. Repository management, code versioning, and deployments were directed across every environment in the migration pipeline, giving a multi-year, high-stakes programme the structure to progress without environment drift or uncontrolled releases. The quality and rigour of the delivery was recognised internally at British Telecom with an "Innovator of the Month" award and official client appreciation.

Key Deliverables

• Spearheaded a large-scale migration of legacy Mainframe systems to a modern ODI 12c architecture for British Telecom
• Designed the IRS2 target architecture as the structural foundation for the entire migration
• Transformed procedural Mainframe code into optimised ODI datasets — re-architecting decades of embedded business logic into a maintainable, modern integration model
• Automated file transfers via Unix shell scripting, replicating and improving on legacy Mainframe job scheduling reliability
• Deployed and managed ODI agents on Oracle WebLogic servers, providing the production runtime layer for the transformed integration logic
• Directed repository management, code versioning, and deployments across multiple environments throughout the migration
• Recognised with British Telecom's "Innovator of the Month" award and official client appreciation for the engagement

Services Delivered

• Data Integration
• Legacy System Migration
• ODI Architecture
• DevOps & Release Management

Tech Stack

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