In the Staff model HMO, physicians typically receive a salary and may even have offices in HMO buildings. The group model is one in which a contract is established with multispecialty medical groups for medical services. In a network model HMO, the HMO has contracts with two or more independent physician group practices to provide health services. And, with an IPA model, or individual practice association, the HMO is contracted with an independent practice association for physician services.