When a major ticket launch opens at the Elbphilharmonie in Hamburg — one of the most sought-after concert venues in the world — thousands of people pick up the phone at the same moment. In years past, more than 80,000 of those calls might hit the switchboard in a single launch window. And most of them ended with a busy signal. The legacy phone system simply wasn't built for that kind of surge.
Today, the picture looks different. Since the Elbphilharmonie migrated its communications onto the Zoom platform, callers no longer get turned away — even during high-demand ticket launches. Getting there started with a fundamental question: how do you replace a telephony infrastructure that has grown and accumulated features for decades, without losing the capabilities that still matter?
About the Elbphilharmonie
Opened in 2017 and designed by the architects Herzog & de Meuron, the Elbphilharmonie has become one of the most recognizable concert halls in the world. Its silhouette — a wave of glass rising above a former warehouse in Hamburg's HafenCity — draws visitors and audiences from across the globe.
The building hosts hundreds of classical, jazz, world music, and contemporary performances each year. For many of them, tickets sell out in minutes. That demand makes service accessibility not just a customer-experience goal, but a fundamental part of how the institution operates.
The challenge
For years, the Elbphilharmonie ran a virtualized PBX system from a well-established vendor. The setup spanned roughly 10 virtual servers and covered an unusually wide range of use cases: business telephony, a call center, a fax server, IP-to-analog converters, audio conferencing, and integrations between internal extensions and mobile phones. "There was almost nothing we couldn't make possible with that system," said Ingo Främbs, deputy head of IT at the Elbphilharmonie.
But that breadth came with a cost. The system had grown so complex that no one on the internal IT team could fully administer it. Even one of Germany's leading integrators depended on the availability of specific specialists. Främbs and his team spent around 2 hours a week just on routine administration — and that didn't account for outages, which occurred every 2 to 3 months and ranged from individual service failures to a complete contact center shutdown. Each incident carried real consequences for customers, employees, and the IT team's workload.
The friction showed most clearly during ticket launches. When thousands of callers tried to reach the hotline at the same time, the PBX couldn't keep up. For a venue that aims to deliver world-class service, a busy signal wasn't an acceptable answer.
The Elbphilharmonie also needed better mobile collaboration. More than 250 employees needed to work flexibly from the office and on the go, and leadership wanted to maintain close contact with teams regardless of where they worked. The existing infrastructure was built for stationary office work and couldn't support hybrid operations.
The proof of concept: skepticism meets a new approach
In November 2021, the Elbphilharmonie began evaluating a new PBX. The IT team started with a detailed sheet of required features and performance data, classified the most important capabilities, and wrote what they called a "cookbook" for a proof of concept. After a round of remote product demos, two vendors remained for a live POC.
Främbs went into that phase with a clear expectation: he wanted to measure Zoom against a requirements document that had been built from daily challenges — hundreds of individual features, plus new collaboration capabilities.
