Embodiments are directed to managing resources over a network. One or more resources that are unassigned. Selection models may be generated based on a one or more open appointments or one or more characteristics of one or more clients. The selection models may be employed to determine each client that is qualified to accept one or more invitations to the one or more open appointments. The one or more invitations to accept the one or more open appointments may be provided to the one or more qualified clients based on one or more notification models that define one or more communication modes to communicate the one or more invitations with the one or more candidate clients over a period of time. An open appointment may be reserved based on a qualified client accepting an invitation to the open appointment.