New
I redesigned the T-site App—to support 100+ technicians managing 50,000+ devices across Germany.
As a freelance designer, I collaborated with PSsystec to redesign PASM’s T.site App, working closely with PASM’s project management, T-Systems software engineers, and the users: technicians from ISS-Communications.
Product
Utility App
Timeline
Q3 2024 - Q4 2024
Skills
Product Design Prototyping User Research & Testing
Collaborators
PASM
T-Systems
ISS
PSsystec
Problem
The complexity of capturing data from metering setups with the T.site app increased – so did the demands on the app itself. PASM desired a redesign that would not only optimize user experience and provide a functional interface but would also be scalable for future IoT initiatives.
Identifying User Needs
To achieve my goal of optimizing the user experience of the T.site App, I first needed to understand the needs of the technicians using it. PASM & ISS provided me with the opportunity to do user interviews and testings. Additionally, I had the valuable chance to accompany a technician for a day to gain further insights.
Pain Points
Controls & Input
The app's controls are partly too small. Controls do not always follow common conventions and have to be learned first.
Navigation
‍The app's navigation is complicated. The technicians want more freedom in navigating and quicker more easy ways to access the content.
Visual Structure
The technicians complain about a lack of visual structure in the app. Content is sometimes not immediately recognizable, which slows down the workflow and can lead to confusion.
Goals
I. Easy data input
Enable fast and intuitive data entry as a core function of the T.site App, supporting users in their daily workflows with minimal friction.
II. Scalable design system
Deliver a seamless user experience and a functional, future-ready interface that supports PASM’s vision for upcoming IoT integrations.
III. Usability
Address the growing complexity of metering setups by evolving the T.site App to meet increasing technical and usability demands.
Solution
Although the technicians work under bright neon lighting, almost 50% wanted a dark mode for the app anyways because it looks cool. If you feel the same, you can switch the project images to dark mode here.
Darkmode
I redesigned the entire information architecture of the app to improve usability and make navigation faster and more intuitive.
For example, the start screen now displays the users most recently created or modified tasks, allowing technicians to seamlessy continue their workflow at the beginning of a new workday.
Design system
To improve usability and ensure long-term flexibility, I developed a modular design system for PASM. It defines reusable components, layout logic, and clear standards for typography, color, and spacing—creating consistent, user-friendly screens.

Just as important: it enables PASM to design and expand new features independently. The modular setup supports quick iterations and seamless future updates.
Icons
I created a small icon set tailored to the PASM/ISS/PSsystec ecosystem. 16x16 pixels, aligned with Google Material Icons, the set ensures scalability for future expansions.
Data input
Data entry is the core function of the T.site App. I redesigned input fields and forms to achieve two key goals: faster workflows and fewer input errors.

The new UI uses clear layouts, validation logic, and smart input constraints to guide technicians through complex tasks. Compared to the old app, this significantly reduces friction – and makes incorrect entries much less likely.
Final Output
The T.site App is live! Furthermore, during the process, it was decided to establish T.Site as a scalable platform for future use across the Telekom Group. Currently, GSUS – Telekom’s real estate unit – is being integrated as a second application. This marks the beginning of a modular ecosystem, designed to support multiple teams and use cases within the organization.
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