 This model is an example of an open-panel HMO, where a physician may maintain their own office and may see non-HMO members.In the network model, an HMO will contract with any combination of groups, IPAs (Independent Practice Associations), and individual physicians.Since 1990, most HMOs run by managed care organizations with other lines of business (such as PPO, POS and indemnity) use the network model.