I'm a ServiceNow certified system administrator and i got my job by having this CSA certificate, but i also had a few interviews before getting the job. I believe if Nokia follow this innovative method will save you lots of resources, plus unselected candidates will apply for different jobs, and this will help nokia advertise their brands as they care about condidates whp doesn't fit the position. Candidates will have a self paced learning without stress. For example first you can offer C++ course for free im addition to other certificates on Nokia's e-learning platforms or Udemy, coursera.... Etc by Nokia academy, then issue certificate of accomplishments and require these certificates in Job description, after, it provide privately interested candidates with 1st challenge at home and then a 2nd challenge in the office should be provided for candidates who shows good results. Finally an HR interview to see if the candidate is able to fit in the team. Last, you can offer further training (soft skills, time & stress management, team work, Nonviolent Communication.... Etc) for not selected candidates and invite them to apply for new openings after finishing the trainings.