Replacing Legacy Cisco Telephony with Microsoft Teams Phone Globally

The client was operating aging Cisco CallManager infrastructure across 100 global sites. Maintenance costs were increasing, disaster recovery was limited, and the legacy phone system was poorly suited to hybrid working.

Cloudbliss started by documenting the existing telephony estate, including Auto-Attendants, hunt groups, call queues, direct dial numbers, routing rules, and country-specific PSTN requirements. These were mapped into a Microsoft Teams Phone target architecture using Direct Routing and AudioCodes Session Border Controllers.

Number porting was managed across multiple carriers and countries, with migration waves scheduled site by site. Temporary forwarding and parallel running were used to protect business continuity during each cutover.

Cloudbliss configured 15 Auto-Attendants with time-based and geographic routing, alongside 8 Call Queues with skills-based distribution. Users were trained on Teams calling across desktop, mobile, and common area phones, with quick reference guides and drop-in support during the first week after migration.

Results

• 1,000 users migrated to Microsoft Teams Phone
• 100 global sites transitioned from Cisco telephony
• 15 Auto-Attendants designed and configured
• 8 Call Queues configured with skills-based distribution
• Migration completed over 12 weeks
• Zero dropped calls during cutovers
• 45% reduction in annual telephony costs
• Legacy telephony hardware dependency removed
• Calling, meetings, chat, and collaboration unified inside Microsoft Teams