Click through if you need advice with personal assistant interview questions or PA interview questions. Why do employers use telephone interviews? Employers usually use telephone interviews when they receive a lot of applications or are recruiting for a lot of positions. It’s a way of narrowing down the candidates into a number that it is possible for them to interview face-to-face. How long do they last? They varied in length, generally takes between 20-25 minutes but can take up to 1 hour. Advantages of telephone interviews: For the employer: They are time and cost-effective – most last about 20-25 minutes. They test your ...