Resource Inventory
The application must inventory the communications resources available to it, then notify TAPI about which resources it will use and how it will use them. See Device Control for additional information on the types of resources and capabilities an application might access.
TAPI 2.x: Applications get the number of available lines when lineInitializeEx returns. They can then perform lineGetDevCaps on each line, lineGetAddressCaps for each address, and lineOpen for each line that will be used.
TAPI 3.x: Applications use ITTAPI::EnumerateAddresses or ITTAPI::get_Addresses to discover the addresses available. ITMediaSupport and ITAddressCapabilities supply information on communication types possible for each address. If implemented by the service provider, ITTerminalSupport gives an application access to additional information and controls.