Process having 3 rounds of interview 1. Assignment given 2. technical interview 3.. Communication round I have spend 1 month to complete assignment also clear the technical interview and they rejected me in 15 min communication round.

Complete process is fraud. First they give you a task / mini project to complete in 1 month. After that they review your code and say your code has some code quality problems. What kind of code quality they are looking for they never tell you before. The moral of the story is they get free project from you added to there company portfolio which they use to get new client projects. If the task can be completed in 2 or 3 days try else don't waster your time.