What the world's first 5G Core SaaS deployment means for operators
A conversation with Citymesh and AWS at Mobile World Congress
For years, our industry has talked about the potential of delivering core network capabilities as a service. At Mobile World Congress this year, I had the opportunity to sit with Robin Leblon, CTO of Citymesh, and Marcel van der Vliet, Senior Global Solutions Architect at AWS, to discuss something different: a deployment that is already live. Citymesh is now running the world's first commercial mobile service on 5G Core as a Service. This milestone represents a paradigm shift in how operators can approach network infrastructure, and the implications extend well beyond a single deployment.
The challenge operators face
When we think about core networks for our customers, we consider the realities many operators navigate: lengthy integration timelines, substantial upfront capex investments, and the operational teams required to manage complex infrastructure.
In our conversation, Robin shared the factors that shaped Citymesh's decision.
Why Citymesh chose this model
As a B2B-focused operator, Citymesh felt that having Tier 1 technology components was important to their business. But Robin was also candid about what they wanted to avoid: the traditional cycle of completing a large deployment only to face significant upgrade projects every six to twelve months. Instead, they wanted their engineering team’s capacity focused on creating customer value, not managing complex infrastructure.
Marcel added context from the infrastructure perspective: deployment speed improves when hardware and infrastructure are ready to use and fully programmable. Less operational burden. Less capital tied up in assets.
The economics mattered too. Traditional on-prem telecom deployments tend to be heavily capex-oriented. The Core as a Service model shifts to a subscription approach; hence no upfront capex, pay for what you consume, and scale as traffic grows.
How we designed Core as a Service
Core as a Service separates control from ownership, aligning with the SaaS concepts that have transformed enterprise software. But applying this model to carrier-grade telecom infrastructure requires a specific architectural approach. We built our solution across three interconnected layers:
- Layer 1: Telecom network. This is the software stack itself comprising 5G core functionality with the carrier-grade performance operators require for voice, signaling, processing, automation, and security.
- Layer 2: Cloud operational model. Automated lifecycle management, programmable APIs, elastic scaling with increasing traffic, and continuous software upgrades. This eliminates the traditional cycle of deploying infrastructure, then having to face a large-scale upgrade project at least once a year.
- Layer 3: Execution by AI and cloud providers. Through our collaboration with AWS, we leverage globally distributed data centers, edge capabilities, hybrid deployment models, and services including AI, data processing, and enterprise security. These three architectural blocks, combined in a structured manner, make Core as a Service production a reality.
What Core as a Service enables
Beyond the deployment model itself, Core as a Service opens capabilities that weren't practical before.
- Faster innovation cycles. With preconfigured use cases and continuous software delivery, operators can introduce new features and services faster. These aren't experimental capabilities. They’re performance-sustained and proven across deployments.
- Subscription access to advanced services. Operators can subscribe to a catalog of services addressing 4G and 5G core requirements such as network slicing, IoT connectivity, automation, and security by design.
- New monetization opportunities. Programmable APIs enable operators to introduce network monetization services rapidly.
What this means for Citymesh specifically
Robin shared how this approach has changed what's possible for them. Moving from a light MVNO to a full MVNO typically requires a certain subscriber scale to justify the investment under traditional models. According to Robin, the Core as a Service model allowed them to make this transition much earlier than they otherwise could have.
He also explained how this transforms their competitive positioning: with this model, they can drive their own roadmap based on their subscribers' requirements. In other words, the infrastructure adapts to their use cases, not the other way around!
What this means for the industry
Citymesh is our proof point that this model is production-grade. We can activate demand-based services where operators pay as they grow. We address the complexity of operations that has long been a barrier for operators considering new approaches. For operators evaluating their options, this deployment demonstrates what's now available: the ability to access carrier-grade core network capabilities without the traditional investment and operational model. Additionally, the agility that Core as a Service provides – with infrastructure that can be deployed in different regions or in hybrid scenarios – makes geographic expansion fundamentally easier.
Watch the full conversation
We recorded our full discussion at Mobile World Congress. If you're exploring how Core as a Service might apply to your network strategy, I encourage you to watch our interview and hear directly from Robin and Marcel about their experience.
