Redesigning Deutsche Telekom’s Self-Care Apps


Interacting with your telco provider without an app is unimaginable in this day and age. From simply checking how much data you have left to paying your bills or resolving issues, all of these functionalities are must-have. The COVID-19 pandemic has only increased the need for self-care channels: most of the world has made jumps in digitalization in the last six months, which would have taken years otherwise.

Across the footprint of Deutsche Telekom Europe, this mission is fulfilled by a self-care app, internally known as One App, a joint effort of central product and IT teams, working closely with local teams in each of the countries.

Besides Germany, Deutsche Telekom owns ten telcos across Europe, and the One App is currently live in nine out of these ten national companies (NatCos). The app appears under different names in the App and Play Store (like “Moj Telekom”, “Můj T-Mobile”, etc.) but it’s a single code base, thus the name One App. It connects to each NatCo’s backend systems by consuming a harmonized API across all of these markets and is supported by a multitude of centrally developed services.

The mission statement of the One App at launch was to replace the various apps that were in place previously, and to funnel the effort across NatCos into a single core product, with a harmonized product vision. To coordinate and deliver this mission, multiple central teams were established in DT Headquarters:

  • The central digital team (us) at the core, which handles the product development and coordinates with all the other central and local teams
  • The central app development team (Deutsche Telekom Digital Labs -DTDL), which develops the frontend clients and various backend components and microservices
  • The central architecture and HAL teams (Harmonized API Layer) which design the APIs which the One App consumes

All of these central teams support the local business and IT teams, who enable and drive the One App in their respective markets.

This distributed working model was a challenge to set up, but doing this heavy lifting early, allowed us to be almost completely untouched by the COVID-19 pandemic. For most of us, our daily routine barely changed and we continued to work unaffected.

The One App initially launched in five NatCos starting early 2018, followed by four additional NatCos the following year. By mid-2020 the app was used by more than 58% of our smartphone customers every month to manage their fixed and mobile services, pay their bills, top-up their prepaid services, resolve their issues, or chat with customer care. And this is just scratching the surface.

Why the redesign?

After launching our initial app version, the number of features kept growing rapidly: from centrally driven features to NatCo requests, the app kept getting more complex, beyond what the initial concept was supposed to support. Our information architecture simply could not sustain adding more features, while keeping them easily discoverable.

Original menu and Redesigned Menu Compared

As an example, the One App was using bottom navigation where only the currently selected menu item would show the label, while all the others would be icon only. This might work for some apps where the features are intuitive, but recognizing the icon for “Top-up” might be not as simple. A similarly difficult journey was the buying of additional mobile data: this very frequent use case was made difficult by burying it behind too many steps.

Creating tutorials to teach the users where to find something, seemed like the wrong approach. Instead, the redesign had to improve on the information architecture.

UX is like a joke. If you have to explain it, it’s not good.

Moreover, the design was simply getting stale (three years is an eternity in app design). Looking at some of the latest trends in mobile design, we were lagging. Compared with our direct competitors, the One App was still a solid product, with good ratings, but that wasn’t something we were satisfied with.

Everyone involved, including the NatCos, started feeling that a redesign should happen rather sooner than later. And while it would be a difficult process, we were eager to take that challenge!

Baby Steps

Before starting with any actual work, we sat down and tried to pinpoint the exact issues we were trying to fix. We did not want to end up doing redesign just for the sake of it. At this point, we also had to ask ourselves how radical the redesign should be: should we try to reinvent the One App, or should this be a rather incremental, evolutionary process?

So we came up with a high-level list of items we wanted to address with the redesign.

  • Improve the Information Architecture to support all current features and allow future extensibility
  • Make the app more intuitive and user friendly by introducing meaningful transitions and micro-animations
  • Make the app UI easier to reuse and extend by implementing a flexible design toolkit
  • Refresh the UI simply to make the app look more modern, covering some frequent customer requests like dark mode
  • No changes to the APIs to ensure no additional effort for NatCos and testing

While we initially had worked with an external agency on the design, we decided to take that work in-house with the Deutsche Telekom Design Hub. A similar process had recently been done with the development team when DT established its in-house development center based in India: Deutsche Telekom Digital Labs. Having dedicated teams for design and development working full-time on the One App was an essential prerequisite to support our fast-paced iterative way of working.

Design Hub had vast experience with similar projects across various digital channels, their brand knowledge was strong, and most importantly, they had the resources to support us long-term. What also spoke to us was their simple but effective vision for the app. Unlike most other proposals we had looked at during our preparation phase, theirs was not as radical but offered incremental improvements and a fresh new vision for the future. And finally, it was the enthusiasm in their approach that sold us on it.

Another crucial element was the full support from management, who had been supportive from the start of the project and understood the importance of this journey. This meant that we even had a certain level of freedom to diverge from usually quite rigid corporate design guidelines. This allowed the teams to be creative and think outside of the box.

Implementing the design

Then the actual work started. At that point, the One App had grown to several hundred screens and screen variants. Design Hub was quick to come up with a basic Design Tool Kit that was to be used across the whole app, but still, every single screen had to be prepared for development. We defined in which order we wanted the features to be redesigned, as this was to be a process lasting at least 3 months if everything went smoothly.

One big challenge we had, was that the development of new features could not simply stop during the redesign! We still had to support the NatCos and their marketing activities and extend on the apps which were live. That meant that our redesign had a moving target. We also did not have the luxury of overshooting our timeline, as the backlog was getting crowded. We divided the app team to have dedicated people working on redesign only. This gave us the resources and focus which was required.

We introduced touchpoints between Design Hub and DTDL, and it was this almost daily exchange that allowed this process to go as smoothly as it did, taking into account the distributed nature of our teams working across multiple time zones.

During the redesign, we wanted to avoid any major changes in functionality, as not to affect any business logic or introduce any API changes. But in the end, we did decide to improve some features, especially regarding managing a service. We were aware that this was one of the weak points in the old design, as users had problems finding certain functionalities. So this screen received a major redesign and required multiple development and design iterations.

“Manage Services Screen” Redesign Process

As the central product team, we were deeply involved in every step of the process. Daily discussions with the design and development teams, micro-decisions at every turn. The redesign process was also completely transparent to the NatCos, and feedback was welcomed at any point. Thankfully their inputs were constructive and supportive. But none of this would have been possible without the commitment of the design and dev teams, whose commitment allowed us to meet our timelines.

Taking it Live

By the time we were satisfied with the design implementation, we were ready for the next step: providing the app to the NatCos for local testing. And this is a challenging process in the best of times. No matter how much time you spend reviewing and optimizing your product, you can hardly know what to expect once it meets the real world. In our case, this meant that we would for the first time see how the app would behave with real-world data (as opposed to our mocked development environment) and how the UI would behave when it made contact with all our different languages, especially Polish and Hungarian, with their long words. No, dear Google: leaving 30% extra space is not enough. 🙂

When this polishing phase had finally finished and we had solved all localization issues, we started to plan how to take the app live. Even though it’s a single code base, the One App is still a separate app in each country, and each local team had to plan their marketing activities around it. In the first NatCo, we launched on Android first and did a staged release: first going with 1% of users, then slowly increasing, fixing minor issues along the way. And all that time, holding our breath.

Commonly, the app ratings take a dive when you redesign an app, and we fully expected it. No matter how good a job you objectively do, some people will dislike it, and those are the same ones that will be very vocal about it. We were just wondering how deep the drop and how long it would last.

But nothing happened. The ratings were mostly stable, and shortly after they even started rising. Crucial at this point was the babysitting period where both the local and central teams would monitor the app behavior and customer complaints and quickly react to it. User feedback on the stores was monitored closely and each valid negative comment was responded to and usually quickly resolved.

Even though the app was ready to launch in April 2020, it took four months to take it live across all markets. And during this time, DTDL had to maintain two different apps, on two different code branches. #hatsoff

App Store Promo Video


Where are we today? The redesigned app is live, and we are focusing on new functionalities to bring to our customers.

Are we perfectly happy with the redesign, and consider our job is finished? Definitely not. A large product like this is never truly finished, and we are constantly discovering and optimizing features and UI. Every day we have to make decisions about whether to spend our time on optimizing small issues or introducing new features. But completing this redesign has created a solid base for more incremental improvements and fine-tuning.

Our backlog and future roadmap are full of interesting ideas and concepts to surprise and delight our customers and turn the One App into more than just a telco app. And even if a self-care app doesn’t sound like a very exciting topic for the average customer, providing the best digital experience will be crucial to keep the most valuable among them loyal for a long time.

To read more about the technical aspects of the One App:

Read more about the One App redesign from Design Hub (in Hungarian):



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