The Warp-Gate is an essential gate for quick travel between solar systems, or even galaxies. It appeared numerously in the Kiddy Grade episodes, as a means of travel. However, as most of the GOTT ships are able to jump through space by themselves, they don't require it.
Kiddy Grade Episode 1 Edit
Kiddy grade Episode 3 Edit
During their time travelling with the C.P.D. to secure the criminal Drake, Éclair and Lumiere went through the Warp Gate. They went from AO4 through H-21 to the center of the galaxy, and were delayed first by 20 minutes due to an accident, then by 3 hours.
Insurers are a group that make their living by raiding prisoner transport ships. Armbrust said that they are like the "life insurence for the underworld". By paying them a certain amount of premium, they can abduct the criminal from it's prisoner transport ship. They attack when a prisoner transport ship gets through the Warp-Gate.