Very often they don't have a specific position in mind, they have a list of roles. The idea is that the phone call helps them understand more about what you're

Very often they don't have a specific position in mind, they have a list of roles. The idea is that the phone call helps them understand more about what you're looking for and then they can share specific roles that match your skills and requirements. At least that's the generous interpretation of how things should work. Personally I try to avoid the open "let's schedule a call" requests if they don't have an attached job description because they don't go anywhere in my experience.