# Opening a conferencing resource

Opening the CNF service with ctaOpenServices enables the ctahd to access to the NaturalConference API. The next step is to open a conferencing resource and obtain a resource handle (cnfresourcehd) to perform actions on the resource.

The following table lists the functions to use when opening a conference resource:

To... | Description
--- | ---
Retrieve a list of resource numbers defined in the system, call cnfGetResourceList with the appropriate parameters. | Returns the resource numbers defined in the NaturalConference configuration file (cnf.cfg). Note: By modifying cnf.cfg you can increase or reduce the number of resources without having to recompile the program.
Obtain a conferencing resource handle (cnfresourcehd), call cnfOpenResource using the resource number obtained with cnfGetResourceList. | Returns a resource handle (cnfresourcehd). This conferencing resource handle has a reference to the ctahd used when opening the resource. Each time you access the conference and member objects, use the cnfresourcehd instead of the ctahd. Wait for the CNFEVN_OPEN_RESOURCE_DONE event before using the cnfresourcehd. This event verifies that the cnfresourcehd was allocated (especially important when using the Server mode of Natural Access).
Retrieve information associated with a conferencing resource, call cnfGetResourceInfo with the returned cnfresourcehd. | Returns a CNF_RESOURCE_INFO structure containing information such as the capabilities of the resource, the maximum number of members the resource can accept, and the number of members available for a new conference. CNF_RESOURCE_INFO also gives you information about the AG or CG board type and board number where the resource is located as defined in cnf.cfg. Use this information to open a switching handle (swihd) associated with this resource. The swihd is invoked when connecting a member of a conference to the trunk interfaces (refer to Establishing the connection).