# Event-handler thread

The event-handler thread initiates the IMGT session by calling imgtStart with one of the following configuration masks:

This mask... | Enables...
--- | ---
0x00000007 | All maintenance messages.
0x0001000 | ISDN-specific messages. (For example, two B channel transfer notification.)

The event-handler thread also performs the following tasks:

- Queries the status of all the B channels in the trunk or NFAS group.

- Queries the status of the D channel.

- Waits and processes any event.