Published on the 11/09/2025 | Written by Heather Wright
In-house Tahi platform frees company…
“Legacy and technical debt will inhibit your business more and more the longer you leave it, and we knew our ability to compete and win was dependent on getting that technical debt out of our business,” says Mark Callander.
The CEO of New Zealand’s third largest telco 2degrees is talking specifically about the company’s ‘absolutely massive’ three-year project bringing together 2.3 million customers connections onto a single platform, following its 2022 merger with Vocus, but he says the issue of legacy and tech debt spans businesses of all sizes.
He told iStart technical debt will ‘absolutely’ limit long-term growth aspiration.
“A lot of companies over-engineer, over-resource, over-project manage versus just getting on and doing it.”
“You have to address it. Too many companies don’t. And where does technical debt start arising? In your call centre, in customer frustration, customer churn and your inability to upsell.
“The most frictionless business is really dependent on having the right technical stack.”
For 2degrees, that ‘right’ technical stack is an in-house built hyperscale platform dubbed Tahi.
Callander says every product, service, system and platform has been replicated in the Tahi business support system (BSS) which is built on open-source technology.
Why build in-house when most others outsource such systems to third-party providers?
For Callander, it’s about control and speed, providing a platform that fits the business and customers, and provides the flexibility to innovate quickly and deliver better customer service, without the bloat or restrictions of third-party systems.
Cost, he says, is a side benefit.
The essence of the new system came across from the Vocus business – as did Callander himself.
“We long had a DNA around building good technology in-house,” he says.
One thing Callander is particularly happy about is that Tahi removes the company’s dependency on traditional big vendors. He’s scathing about the previous (in fact, current) vendor, a big name brand whose contract with 2degrees is days away from being terminated.
“These companies’ tax your success. The bigger you get the more licensing they get for really adding no more value to your business. Anytime you partner with anyone who simply taxes your success, it’s just not the right balance.”
That’s not to say 2degrees isn’t still partnering. Callander says it does partner with other companies which add value to the business. “That’s a good value exchange.”
With a team of around 130 in its IT team, 2degrees was well-placed to develop its own platform. Even so, he says it wasn’t an easy task.
“When you do a large-scale integration, the rest of your business kind of goes on hold. If you have lots of stuff in the old system that you need to move to a new system, you want to develop and build as little new stuff in the old system as possible.”
That might be fine if you weren’t in a competitive market, but in a competitive market, where you have to respond to changes, it creates vulnerability, he says.
“We had to minimise as much development in the old system and get into the new system and maintaining growth though that period given the complexity of change was a phenomenal outcome.”
2degrees has already seen the benefits. It launched a new roaming product in two weeks and Callander attribute’s the company’s N4L (Network for Learning) win last year, alongside Palo Alto Networks, to the software stack built on Tahi.
The company’s partnership with AST SpaceMobile, announced in March, will also harness Tahi to design and build new products, even though it is third-party infrastructure being accessed.
Callander says the integration highlighted aspects of the ‘old world’ the company didn’t like, including customer processes that weren’t seamless, requiring customers to jump out of the digital experience to speak to a person.
“Now we have control of our own platform, we’re going to back and enhancing customer experience through our traditional business processes. We have a big focus on CX improvements now we are in our own world, our own BSS and can start invigorating and changing what our customers see.”
Up to 50 changes a day are currently flowing into Tahi.
Because it is built on open source, with open APIs, Tahi can be integrated with a raft of third-party providers, opening the doors for seamless integration with other tech providers where they add value.
“In our old world, the thought of introducing another technology platform with the legacy we had was just impossible,” he says.
“Our new ecosystem is limited only by our team’s imagination.”
Tahi brings together all mobile, broadband and energy products across all market segments, including consumer, SME, enterprise and public sector.
“It’s the heart and brains of the organisation,” Callander says. “It essentially runs our end-to-end business, from the moment a customer touches our website to sign up with us, through the full lifecycle and sending out bills, how things appear in an app…”
The Flex front-end customer portal, largely targeting larger enterprise and government customers, enables customers to manage very large and complex services in one place and in real-time.
Of course, less need to customers to interact with staff means less need for certain staff. Callander admits 2degrees has less staff in its contact centres today, but says there has been no restructuring with contact centres experiencing a 30 percent natural attrition annually.
“As we have continued to roll out features of Tahi, customers have had to call less and attrition has taken affect.”
On the flip side, however, the company is actively hiring more local developers.
“We are getting higher skilled labour in our workforce and really positioning ourselves as a software company moving forward.”
Getting cultural
Callander says the tech aspects of the project weren’t the hard part. It was the cultural piece which was the toughest part.
“You’re bringing together two teams who will have different views around which stack is better.”
The key in the first 12 months post-merger was ‘building hearts and minds and company-wide conviction that the direction we were taking the business was the right direction’.
Callander cites a phrase he often uses: Show, don’t tell.
“You have to show people the benefits of the new system. You can tell them about it until you are blue in the face, but it’s not until you put it in the hands of end users or customers that they really understand.”
One of the first things the business did in the integration program was move a retail store across to the new stack. It reduced the signup process for new customers from 40 minutes to less than 10 minutes.
“All of a sudden, you’ve got staff raving about Tahi because of the real impact it had on their jobs. That’s a really good example of show, don’t tell,” he says.
Despite Callander’s enthusiasm, he admits it wasn’t an easy project, and not everything went right.
“We can sit here and say how amazing it was, but it’s been a hard journey. We got most things right. We set a culture where people can move at pace, some things break but we learn from them and that pace of change and the way we operate as a business was a key enabler to getting it done in three years.
“A lot of companies over-engineer, over-resource, over-project manage versus just getting on and doing it.”
As to the future, Callander says the company has big growth aspirations: It has set an ambition of growing faster in the next three years than it did in the previous three years.
“Those growth aspirations can only happen through having the culture piece right, but now we’ve got the technology piece right too.”
