The product team asked me to customize upcoming T-Mobile brand phone UI. After back and forth discussions with the product team and OEM, I determined some critical areas for customization and sent the design document over to the device manufacturer (OEM) after getting approval from the product team.


OEM provided a sample T-Mobile branded Android phone with Google Pixel standard UI. The product team realized the interface was standard with Google blue themes and overly simplified interactions. They would like me to customize the essential native apps with “T-Mobile look and feel”. Moreover, there were some UI interaction/ display problems in the native app. I needed to identify them and provide solution for improvement as well.

My role:

As the only UX person, I worked with the product team to identify native apps UI flaw and came up with a solution (mockup) accordingly. In addition, I provided a color design guideline to customize the native messaging/ calling applications with T-Mobile branding.


  • Delivered a benchmark guideline document to OEM for the phone UI customization.
  • Determined color selections for both dark and white themed native app display.


The product team received a sample phone from OEM for T-Mobile branded phone, which they planed to launch to the market with new magenta themed hardware–a slick magenta button on the side with beautiful patterns and a T-Mobile logo on the back. However, when the team turned on the phone, they found “the look and feel was very native Google Pixel” as what they told me. Moreover, when the product team tried messaging and calling on the sample phone, they found it awkward to operate but could not pinpoint out the reason why. Owing to the limited time and resources, the team asked me to determine hot fixes on the UI side to bring T-Mobile branding to the phone, and provide better user experience in the native apps.

A color guideline for best matching colors with T-Mobile colors.

First of all, I provided the low-hanging fruit solutions to reach the goal of “T-Mobile look and feel” — change colors on the app UI. I looked into color wheel and determined colors that will match with T-Mobile enterprise themes best, and provided a quick mockup with the product team.

It took us several rounds of discussions to make the change since there were some restrictions on the OEM side to customize Android native apps, but eventually after some negotiations with developers, we made a deal to agree on items to proceed.

Second, I quickly tested the flow and UI with users to spot the most critical change needed in the native messaging/ calling apps. After testing with 9 users, I spotted some obvious flaws and quickly mocked up solutions for retesting. Later on, I presented my finding to the product team, and made a benchmark guideline after reaching agreement with the product team.

I found quick design iterations were very helpful for both communication between the stakeholder, OEM, and user testings. In doing so, I effectively inserted T-Mobile style into the native apps while making these app more user friendly than the original version.

Here are some example pages of my redesign. The original document that I provided to OEM had more requirements than the final version. I learned when negotiating with developers for UX fixes, as a designer, I had to get ready for back and forth meetings about how to reach the best fixes without using too much resources for development. Though it took time, I found the process interesting and rewarding.

Thank you for reading! If you would love to know more about this project, please email me. I am more than happy to share my experience with you.

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