Three App: Registration and login


When I started on this project, only 19% of users could successfully register on a first attempt. 

I investigated the issues and proposed solutions that included:

  • New User Interface Design

  • Introduction of a help centre

  • New functionality to 'Open email' 

  • Better copy including error messages

  • Updated flow to improve login and biometrics


rise in successful


fewer monthly
customer complaints


approximate monthly
saving to Three


Investigating the issues with registration journey was broken down into four research methods.

My personal experience

I registered myself on the app and documented all my thoughts around my experience of registration process. 

Documenting the flows

I created a flow to include all possible journeys including happy paths, unhappy paths and all potential error messages.

Qualitative research

I spoke to staff in the call centre to find out the most common problems. I read app store and survey reviews and spoke to users who recorded their experiences. 

Quantitative research

Working with the Analytics Team I looked into the steps users were going through, and where they dropped off. 



From the research conducted we identified a number of issues.

  • The app incorrectly identified some phone numbers and sent users down a login journey rather than registration.

  • The input fields jumped around the screen when the keyboard was activated and many of the error message were not helpful.

  • When a device or SIM was purchased, the email entered at checkout was automatically assigned to the SIM, but the user was not notified at the time.

  • The process of validating an email address took the user off to the website with no way to get back to app. 

  • User who didn't complete registration ended up in a state of partial registration which was impossible to get out of without calling the call centre.

  • Error messages were unclear.

  • Small devices were fiddly to use as all the information was crammed into one small area.


Improved flow

The app allowed people the fully access the app after initial registration, meaning there was no need to login after first time registration. We also added the ability recognise partially registered users and drop them at the correct step. 

Biometrics were given increased prominence as that proved to be the most successful login method.  


Help centre

One of the issues identified in the research was the large number of queries made to call centre and live chat services from users struggling to register. 

We introduced a help centre to assist the user to self serve. The help centre addressed the the most common FAQs and provided solutions including access to live chat and call centre.  


Open email functionality

We added an 'Open email' button to open the users email directly from the app. We also added a 'Back to App' button from the validation success screen. This created a more seamless journey and resulted in fewer partially registered users.


Redesign user interface

I designed a new user interface for a fresh look and feel. The cleaner design made better use of the available space on mobile devices and take up less space on devices. This allowed us to support small devices and use icons to assist with instructions. 

We added clearer instructions, icons and error messages to explain what a user needed to do at each step. 


We tested the new journey with a select group using User Zoom.


We created a prototype and asked participants to go through the process and perform a think aloud recording. 

Almost 70% of users found the instructions easy to follow and all participants successfully registered.

Some people commented that there was no success screen at the end of the process and that is the one change that we will be taking into the next iteration. 

Overall the registration design was successful, clear and easy. We moved forward and built this design with tracking so we could monitor is over the following months. 


of users found process easy


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New designs were rolled out over a period of three months. We kept a close eye on the feedback and the statistics and iterated when we saw opportunities to make improvements.  

Over the course of the project, the registration journey was the biggest success story. We saw:

  • Call centre complaints drop by 50,000 per month over six months. Each call cost £2.20 so the saving was over £100,000 a month.

  • Positive reviews began to trickle through the App Store. 

  • Successful registration went from 19% to 71%. An increase of 270%

  • Successful email validation doubled from 35% to 69% in six months.

  • Forgot password taps reduced by almost 50%. Going from 176,707 in Jan 2020 to 90,866 in Aug 2020. 

iOS Login Reg 2020.png


rise in successful


fewer monthly complaints