•This paper investigates when AI or human salespeople serve B2B buyers better.•This paper develops a framework to affect the relative effectiveness of AI.•This paper provides propositions on the relative effectiveness of AI across the buyer–seller relationship stages.•This paper provides a solid foundation which future researchers can build upon. Given the infusion of artificial intelligence (AI) in B2B sales, AI salespeople perform required sales tasks more effectively than human salespeople in some contexts but not in others. To gain insights about the contexts in which the relative effectiveness of AI over human salespeople varies, this conceptual paper develops a framework which systematically organizes contingency factors. Further, by combining the relationship lifecycle theory with AI job replacement theory, this paper provides well-grounded propositions about when AI or human salespeople perform better for buyers in distinct relationship stages with the seller. The paper concludes with implications and future research directions on the adoption of AI in B2B sales. In doing so, this paper provides a solid foundation which future researchers can build upon and enriches the discussion about the contingency factors, the changing roles of human salespeople, and how to structure sales organization with AI and human salespeople.