Face-to-face and they will fly and board you to where ever the IBM unit is based. They will ask questions that will how your competence in the field you are applying for.

you get referred. then you apply to a referral link , after that they will call you to schedule tech round which will be over webex. you need to carry identity proof. Once you are tech select then another round of interview will happen for (PDM) round it will be HR + tech as well.