What is a tell in Travelers?

What is a tell in Travelers?

The future-folk come back to our time via T.E.L.L. (time, elevation, longitude, latitude) technology that lets people do the soon-to-be-deceased body-jumping thing. Thousands of Travelers already live in the present. Jan 12, 2017

See also  How much does it cost to be medically evacuated from a cruise ship?