Replacing Legacy Telephony with Microsoft Teams Phone — Globally

The Problem with Legacy Phone Systems

Enterprise telephony has been one of the last holdouts of on-premises infrastructure. While email moved to the cloud years ago and file storage followed shortly after, many organisations still run aging PBX systems or on-premises Cisco, Avaya, or Mitel platforms. These systems are expensive to maintain, require specialist hardware engineers, offer limited disaster recovery, and provide almost no mobility for hybrid workers.

The maintenance contracts alone can be staggering. Hardware refreshes are cyclical and costly. And when something breaks, the organisation is dependent on a shrinking pool of telephony engineers who specialise in legacy platforms. Meanwhile, every employee already has Microsoft Teams on their desktop and mobile device — a platform that now includes enterprise-grade telephony capabilities.

Why Teams Phone Is Not Just a Softphone

There is a common misconception that Microsoft Teams Phone is simply a softphone bolted onto a chat application. The reality is that Teams Phone has matured into a full enterprise telephony platform supporting PSTN connectivity through Microsoft Calling Plans, Operator Connect, or Direct Routing via Session Border Controllers. It supports Auto-Attendants with multi-level IVR menus, time-based routing, and holiday schedules. Call Queues can be configured with skills-based routing, overflow handling, and real-time reporting. Emergency calling with dynamic location services, compliance recording, and integration with existing contact centre platforms are all part of the offering.

For organisations already invested in the Microsoft ecosystem, Teams Phone eliminates an entire category of infrastructure and the operational overhead that comes with it.

The Cloudbliss Approach to Global Telephony Migration

At Cloudbliss, we have architected and delivered Teams Phone deployments across multiple countries, handling the complexity that comes with different PSTN regulations, number porting requirements, local emergency calling obligations, and user expectations shaped by decades of traditional phone system usage.

Architecture and Design. Every deployment starts with a detailed call flow analysis. We document every existing Auto-Attendant, hunt group, call queue, and direct dial number. We map these to their Teams Phone equivalents and design the target architecture, including SBC placement for Direct Routing, Calling Plan assignments, or Operator Connect configurations depending on the requirements and geography.

Number Porting Strategy. Number porting is often the most time-sensitive element of a telephony migration. We manage the porting process end to end, coordinating with carriers across multiple countries, scheduling port dates to align with migration waves, and maintaining temporary call forwarding during transition windows.

Call Flow Configuration. We build Auto-Attendants and Call Queues in Teams to replicate and improve upon existing call flows. This includes multi-level IVR menus, time-based routing for business hours and holidays, skills-based call distribution, voicemail-to-email integration, and shared line appearances where required.

Site-by-Site Migration. Global deployments require a phased approach. We migrate site by site, running parallel systems during the transition period so that if any issue arises, calls can be rerouted back to the legacy system within minutes. Each site migration follows a proven runbook with pre-migration testing, go-live support, and post-migration validation.

User Training and Adoption. Telephony is deeply habitual. Users have spent years reaching for a desk phone without thinking. We provide targeted training covering Teams calling on desktop, mobile, and common area phones. We create quick reference guides and run drop-in sessions during the first week after each site migration.

A Real-World Result

A multinational organisation with 1,000 users across 100 global sites was running aging Cisco CallManager infrastructure with escalating maintenance costs, poor disaster recovery, and no support for hybrid working. Cloudbliss architected a Teams Phone deployment using Direct Routing with AudioCodes SBCs, designed 15 Auto-Attendants with time-based and geographic routing, configured 8 Call Queues with skills-based distribution, and managed number porting across multiple carriers and countries. The migration was executed site by site over 12 weeks with parallel running at every stage. Not a single call was dropped during any cutover. The organisation achieved a 45% reduction in annual telephony costs, gained full mobile and desktop calling for every user, and eliminated the dependency on legacy hardware entirely.

The Outcome

The client now operates a unified communications platform where calling, meetings, chat, and collaboration all live within Microsoft Teams. Disaster recovery is inherent in the cloud architecture. New sites can be provisioned in hours rather than weeks. And the IT team no longer needs to maintain specialist telephony knowledge for a legacy platform that was becoming increasingly difficult to support.

Is Your Phone System Holding You Back?

If your organisation is still running legacy telephony infrastructure, or if you have already started exploring Teams Phone but need expert guidance on Direct Routing, call flow design, or global number porting, the Cloudbliss team can help. We offer a Teams Telephony Assessment that gives you a clear migration roadmap, cost comparison, and timeline.