It is not common for recruiters to call candidates to reject them. Most often, rejection is communicated through email or through the applicant tracking system. However, some recruiters may choose to call candidates to reject them if they feel that it is the most professional or respectful way to do so. Additionally, if a recruiter has built a relationship with a candidate and feels that a phone call is the best way to provide feedback, they may choose to call instead of emailing. Ultimately, it is up to the discretion of the individual recruiter.