I have a SMT-i5243 but I don't know to use the webcam.
I have installed it OK.
How can I made a videocall through trunks?
How can I made a intercom videocall?

You can't make video call through trunks (other then via spnet to a video capable phone on another system)

ICM Video call should happen automatically when you call another video enabled phone (softphone, ITP-video (5100v), sip video phone under 4.60b firmware)

Thanks!! That's what I wanted to know.

Additionally, Is possible to make a video conference with the OS7400 through Trunks with other videoconference systems with another way?