An in-network medical provider is within the approved network of providers for a particular health plan. Out-of-network providers are not on the list. If you visit a doctor within the network, the amount you will be responsible for paying will be less than if you go to an out-of-network doctor. In many cases, the insurance company will not pay anything for services your receive from outside their network; however, there are exception to this. As a general rule, HMOs tend to have smaller provider networks than PPOs. In HMO and PPO plans, referrals to specialists will be to doctors within the network. Indemnity plans typically do not have networks; you go to whatever doctor you want.