Zero-Downtime Migration from AWS to Azure for Mission-Critical Telecom Billing Platform
Successfully migrating a complex telecom billing system with minimal documentation and zero service disruption
Overview
A specialized telecom software provider based in Pune delivering billing and operations support systems to telecom operators across South Asia and the Middle East. Their platform processes over 50 million call detail records (CDRs) daily and manages billing for approximately 15 million subscribers.
Following acquisition by a larger technology conglomerate with significant Azure investments, the company needed to migrate their AWS-based infrastructure to Azure while maintaining strict service level agreements with telecom operators who depend on their system for revenue operations.
Business Challenges
Complex AWS Infrastructure
Highly customized AWS environment built over 6 years with minimal documentation
Interconnected 30+ EC2 instances across multiple availability zones
Complex networking setup with VPC peering, Transit Gateway, and Direct Connect components
Heavy reliance on AWS-specific services like DynamoDB and SQS
Knowledge Gaps
Original infrastructure architects no longer with the company
Limited understanding of existing deployment processes and dependencies
Missing documentation for critical configuration parameters
Uncertainty about exact data flows and integration points
Business Continuity Requirements
Contractual SLA requiring 99.99% availability during business hours
Maximum allowed maintenance window of 4 hours during monthly upgrade cycles
Regulatory requirements for data residency and encryption
Need for minimal disruption to ongoing development activities
Our Solution
We implemented a methodical, phased migration approach with comprehensive discovery, parallel environments, and seamless cutover strategy.
Assessment & Strategy
We conducted a thorough discovery process to understand the existing infrastructure and develop a detailed migration plan that minimized risk.
Infrastructure Discovery
Deployed automated discovery tools to map AWS resources and relationships
Created comprehensive infrastructure documentation with dependency mapping
Conducted interviews with key stakeholders to uncover undocumented requirements
Performed network traffic analysis to identify communication patterns
Migration Planning
Developed detailed mapping between AWS and Azure services
Created environment-specific migration strategies (dev, test, production)
Designed hybrid connectivity architecture for gradual transition
Established success criteria and rollback procedures for each migration phase
Risk Assessment
Identified critical business processes and their infrastructure dependencies
Conducted failure mode analysis for each migration step
Developed contingency plans for potential migration challenges
Created detailed testing strategy for functionality validation
Business Impact & Results
Migration Success
•Completed migration 8 days ahead of schedule with no service disruption
•Achieved 100% data integrity with no reconciliation issues
•Successfully processed 52 million CDRs on day one in Azure
•Zero customer-impacting incidents during transition period
Enhanced Performance
•CDR processing time reduced from 42ms to 30ms per record
•Database query performance improved by 35% after optimization
•API response times decreased by 22% in Azure environment
•Billing cycle processing time reduced from 6 hours to 4.3 hours
Enhanced Operations
•Reduced disaster recovery time from 4 hours to 85 minutes
•Improved backup success rate from 97% to 99.99%
•Enhanced monitoring providing 3x more granular visibility
•Decreased mean time to resolution for incidents by 40%
Business Benefits
•Consolidated licensing costs by integrating with parent company's Azure agreement
•Reduced operational overhead through improved automation
•Eliminated data transfer costs between applications
•Streamlined vendor management with single cloud provider
"VegaStack's expert planning and execution enabled a zero-downtime migration of our complex billing platform. Their methodical approach and ability to recreate our AWS environment in Azure improved both performance and disaster recovery."
Key Takeaways
Discovery Importance
Thorough discovery and documentation of the existing environment was critical to migration success.
Parallel Processing Strategy
Maintaining parallel processing environments with data synchronization eliminated the need for extended downtime.
Rehearsal Effectiveness
Multiple migration rehearsals identified subtle issues that would have caused production problems.
Knowledge Creation
Creating comprehensive documentation throughout the process built a foundation for ongoing operations.
Conclusion
This engagement successfully migrated a complex, business-critical telecom billing system from AWS to Azure while maintaining continuous operations. By taking a methodical approach focused on discovery, risk mitigation, and incremental transition, we helped the client achieve their post-acquisition integration goals without disrupting their telecom operator customers.
The migration has positioned the company for better integration with their parent organization's technology ecosystem while improving performance and disaster recovery capabilities. With comprehensive documentation and knowledge transfer completed, their team is now confident in operating and evolving their platform in the Azure environment while meeting the stringent availability requirements of the telecom industry.
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