It was unveiled at the Millennial Fair in 1000 A.D. Both Crono and Marle assisted with the demonstration. But when the Telepod was activated, the energy reacted to Marle's pendant, sending her through time. Crono then used the Telepod again to find her.
Using the Time Gate created by the Telepod, Crono and his friends finally return to 1000 A.D.