AWS Mainframe Modernization: transforming telco from legacy constraints to digital innovation

Legacy mainframe systems remain the backbone of many telecommunications (telco) operators, despite rapid technological evolution. These systems, combining proprietary and vendor-developed applications, remain critical for handling bulk data processing and large-scale transactions. These systems typically handle critical Business Support Systems (BSS) and Operational Support Systems (OSS) workloads, such as the highly transactional processes of rating, charging, and billing. Mainframes can simultaneously process millions of transactions with high reliability, which is ideal for telco providers who need continuous, error-free performance. As customer expectations for digital services and real-time interactions have increased, telco providers face mounting pressure to modernize their infrastructure while maintaining the robust processing capabilities of mainframe systems. Telco providers are increasingly integrating mainframes with advanced technologies such as cloud and mobile applications due to changing customer behaviors and increased data traffic from mobile services.

Why should telcos modernize their mainframe systems?

The progressive digitalization of telecommunications has incrementally introduced complexities in multiple modules such as billing, mediation, and charging systems, culminating in the advanced challenges of 5G. These evolving models—including network slicing charging, and B2B2X billing—require highly agile business support solutions capable of rapid adaptation to changing market demands and technological innovations.

Traditional mainframe environments, characterized by proprietary tools and tightly integrated data models, struggle to meet the agile, scalable, and innovative requirements of modern telecommunications operators. The need for rapid deployment, scalability, fail fast approach and the ability to innovate without extensive coding makes it challenging for mainframes to support new models effectively. Additionally, implementing DevOps practices on mainframes is difficult due to proprietary tools and the complexities involved in integrating them with modern CI/CD pipelines. Furthermore, deploying distributed systems and microservices architectures on mainframes remains problematic due to their multitenant design. All applications share the same operating system environment, limiting independent service scaling and increasing the blast radius of failures.

Compounding these challenges is diminishing mainframe expertise, leaving organizations at risk of losing critical application knowledge to enhance their legacy systems. Telecommunications providers are increasingly pressured to modernize their IT infrastructure to reduce costs, enhance agility, and accelerate deployment of new digital services. This transformation is critical in the fast-paced 5G era where providers must embrace cloud computing and hybrid IT environments to remain competitive. The shift towards agile, scalable solutions is essential for telcos to meet the current 5G demands while positioning themselves for the future.

AWS Mainframe Modernization Service

AWS offers a comprehensive Mainframe Modernization service that provides managed tools and services for migrating and modernizing mainframe applications and data to AWS infrastructure. It provides a platform for analyzing, developing, testing, deploying, and operating modernized mainframe workloads on AWS, enabling telcos to enhance their agility and customer responsiveness.

AWS Mainframe Modernization service enables refactoring and replatforming, along with data replication, by supporting multiple modernization patterns that are critical for telco operators. The service offers specialized tools such as AWS Blu Age for refactoring, complemented by partner solutions. AWS Mainframe Modernization service integrates with core AWS services such as AWS CloudFormation, AWS PrivateLink, and AWS Key Management Service (AWS KMS), while maintaining alignment with industry compliance standards. This enables telcos to meet regulatory garequirements throughout their modernization journey.

Furthermore, AWS provides a fully managed runtime environment with self-healing compute and API-driven scaling capabilities, supporting uninterrupted service for millions of subscribers. The CI/CD feature accelerates migration speed and reduces time-to-market for new services. With an extensive ecosystem of AWS Mainframe Modernization partners and telco expertise, AWS helps telco organizations transition to modern cloud infrastructure efficiently, and enables them to compete effectively in the evolving digital landscape.

Figure 1: AWS Mainframe Modernization service

Accelerating BSS/OSS refactoring and modernization with AWS Blu Age

AWS Blu Age, integrated into AWS Mainframe Modernization, provides a comprehensive solution for automated mainframe modernization through its powerful tools that accelerate the refactoring of mainframe applications, such as code, dependencies, and infrastructure. The platform refactors legacy applications written in COBOL, PL/1, RPG/400, COBOL/400, and JCL, along with their associated databases such as Db2, Db2 for i, VSAM, IMS, and IDMS. These applications are transformed into modern, cloud-ready solutions using technologies such as Angular and Java/Spring Batch, and databases such as PostgreSQL, Db2 (LUW), Oracle, and other AWS purpose-built relational databases.

The AWS Blu Age suite comprises powerful tools such as Blu Insights, Transformation Center, Data Migration Suite, and Testing Suite. Blu Insights provides a comprehensive understanding of legacy applications, identifying dependencies and generating insights critical for effective modernization planning. Transformation Center automates the transformation of legacy application code (such as COBOL or PL/I) into modern, cloud-ready languages such as Java, maintaining functional equivalence and optimized performance. Data Migration Suite helps to migrate mainframe data to cloud platforms compatible with the refactored code and schemas. AWS Blu Age Testing Suite facilitates rigorous validation by automating both functional and regression testing to confirm the accuracy and reliability of converted applications.

For telco BSS and OSS, AWS Blu Age can help with industry standard design patterns and best practices, using cloud services to transform monolithic applications into flexible business components and macro-services. Automating the refactoring of the complete telco software stack – such as billing systems, customer management platforms, and network inventory, service fulfillment, and assurance application – allows AWS Blu Age to significantly reduce modernization timeline and costs. The platform effectively balances legacy business rules with cloud-native benefits while mitigating risks associated with complex BSS/OSS transformations. The modernized BSS/OSS applications deliver enhanced scalability and agility necessary for 5G services, real-time charging, and improved digital customer experiences. These transformed systems support streamlined maintenance while preserving critical telco business rules, with automated testing capabilities validating the reliability and accuracy of complex telco workflows.

Figure 2: AWS Blu Age high availability architecture across two Availability Zones

Re-imagining legacy telco systems: AI-powered transformation with Amazon Q Developer

Amazon Q Developer is an innovative AI-powered tool designed to accelerate and streamline the modernization of legacy mainframe applications. It supports all patterns of mainframe modernization, providing comprehensive solutions across different transformation approaches. This service, currently in preview, uses generative AI and autonomous agents to transform COBOL-based mainframe workloads into modern, cloud-optimized Java applications. Amazon Q Developer harnesses agentic artificial intelligence (AI) frameworks to accelerate mainframe application modernization with less human intervention. It aims to help customers streamline their mainframe modernization journey, from initial analysis and planning to code transformation and migration.

Amazon Q Developer systematically modernizes legacy telco applications through phases: comprehensive code analysis, documentation, application decomposition, migration wave sequence planning, and code refactoring. It provides an autonomous, objective-driven approach to application modernization, allowing customers to define high-level goals. Then, Amazon Q Developer orchestrates AI agents and human actions to analyze the codebase, decompose monoliths, document business logic, transform code, and manage overall modernization tasks. Amazon Q Developer combines these capabilities to empower telco operators to modernize critical OSS/BSS mainframe systems with speed and cost-efficiency, while preserving essential business logic. This AI-powered solution equips customers with subject matter expertise to reimagine legacy code, transform monolithic systems into microservices, and modernize platforms to support real-time 5G services.. Amazon Q Developer uses adaptive reengineering approaches accelerates the evolution of network inventory and service assurance applications to meet the demands of 5G network slicing and edge computing.

Modernizing telco data: mainframe to cloud data replication

For data replication patterns, AWS Mainframe Modernization Data Replication with Precisely uses Change Data Capture (CDC) technology to enable near real-time data replication. This can be used to extract data in real-time from complex mainframe databases such as Db2 z/OS, IMS DB, and VSAM files, seamlessly transferring this information to a wide range of AWS database platforms. On the AWS side, the service supports multiple Amazon Relational Database Service (Amazon RDS) offerings such as Amazon Aurora, Microsoft SQL Server, MySQL, Oracle, and PostgreSQL, with the capability to further synchronize data through Amazon Managed Streaming for Apache Kafka (Amazon MSK) to platforms such as Amazon S3, Amazon Redshift, and Amazon DynamoDB. CDC replication facilitates high-fidelity, low-overhead data migration across systems.

This comprehensive data migration approach enables telco operators to modernize billing and customer data systems, seamlessly migrating subscriber records and usage data without interruption. It supports critical 5G use cases by facilitating real-time synchronization between legacy and cloud-based charging platforms, enabling dynamic service provisioning and usage-based billing.

Figure 3: Data replication for IMS database using Precisely Connect

Streamlining telco file migration: mainframe to AWS Cloud

AWS Mainframe Modernization File Transfer streamlines and accelerates mainframe dataset transfer to Amazon S3. It automates dataset discovery, streamlines transfers, and converts code pages by supporting sequential, PS, GDS, GDG, and VSAM KSDS. Installing a File Transfer agent on the mainframe facilitates communication and supports seamless migration. Users create data transfer endpoints for connectivity and scalability, which are crucial for large data volumes. Through the AWS Management Console, customers select data sets, specify options, and initiate transfers with minimal operational disruption.

For telco companies, this solution enables efficient migration of historical customer records, call detail records (CDRs), and network configuration files from legacy mainframe systems to the cloud. This facilitates advanced analytics and improves operational efficiency while maintaining data integrity and security.

Figure 4: File transfer architecture

Validating modernized telco applications: mainframe to cloud testing

AWS Mainframe Modernization Application Testing is a cloud service for automating mainframe application tests.

It supports customers validating that modernized apps maintain functional equivalence with their legacy counterparts. This feature automates test case management, data capture, and result comparison. Furthermore, it uses AWS cloud scalability to allow telco organizations to run multiple tests simultaneously, cutting timelines and boosting efficiency. And it integrates with CloudFormation for consistent, repeatable test environments, thereby enhancing cost-efficiency and reliability.

For telco operators, this solution is particularly valuable for validating critical BSS workflows such as billing cycles, customer provisioning, and service activation processes. This makes sure of a seamless customer experience during the modernization journey.

Security and logging for telco with AWS Mainframe Modernization

Telco operators face stringent data sovereignty rules and local regulations. AWS Mainframe Modernization implements robust security and logging capabilities, which are essential for telco applications to maintain data protection and operational integrity during the modernization journey. The service adheres to the AWS shared responsibility model, with AWS managing infrastructure security while telco customers secure their data and access controls.

AWS Mainframe Modernization provides comprehensive security features tailored for telco operations, including AWS Identity and Access Management (IAM) integration for fine-grained access control to BSS/OSS resources, encryption for subscriber data (AWS KMS, TLS 1.2+), and AWS PrivateLink for secure connectivity between VPCs and AWS services. The solution implements enhanced security through network isolation and AWS WAF protection for customer-facing services.

Logging and Monitoring features provide comprehensive observability through Amazon CloudWatch integration for real-time KPI monitoring and custom operational dashboards, along with centralized logging for billing systems, customer platforms, and network inventory applications. The solution enhances security posture through AWS Security Hub and Amazon GuardDuty integration, enabling threat detection and protection against fraud while maintaining complete audit trails through AWS CloudTrail for regulatory compliance.

These features enable telco operators to achieve robust security, regulatory compliance, and efficient monitoring as they migrate critical BSS/OSS systems to the cloud. This comprehensive approach supports the unique requirements of telco modernization, from securing customer data to maintaining operational visibility across transformed systems.

AWS partner ecosystem for telco mainframe modernization

AWS Marketplace and Competency Partners provide a comprehensive ecosystem for telco mainframe modernization, combining pre-vetted migration tools with specialized expertise in telco transformation. This ecosystem features AWS-integrated technologies from leading vendors for assessment, migration, code refactoring, and data replication, which enable rapid deployment with streamlined procurement. Partners possess multi-disciplinary competencies spanning cloud migration, data analytics, and AI/machine learning (ML), with specific focus on OSS/BSS platforms modernization.

These validated partners deliver end-to-end services such as migration assessment, transformation roadmaps, and risk mitigation strategies tailored to telco infrastructure challenges. Their approach encompasses system evaluation, proof of concept, incremental migration, and optimization, while addressing telco-specific regulatory and operational requirements. Teco organizations use this comprehensive partner ecosystem to accelerate modernization initiatives, reduce complexity, and achieve predictable transformation across various modernization strategies, all while maintaining compliance and operational integrity.

Conclusion

AWS Mainframe Modernization enables telco providers to transform legacy systems, thereby mitigating modernization risks and adopting flexible, variable-cost models. Advanced tools such as AWS Blu Age and Amazon Q Developer accelerate cloud innovation while preserving business logic. Enhanced security and logging features, along with streamlined AWS service integration, improve operational efficiency and compliance. Supported by AWS Mainframe Modernization Competency Partners, this transformation lays a foundation for advanced analytics and AI, positioning telcos to thrive in the 5G era and drive digital growth.