Activate by saying:
"Ok Google, talk to CharlieChat ..."

Examples:

"... about the next southbound train from Harvard"

"... about eastbound trains from BU West"

"... about the Red Line northbound trains from North Station"

Know exactly when to leave for Boston's T

"OK Google, talk to CharlieChat about the next southbound trains at Harvard."
The next Southbound Red Line train at Harvard is 3 minutes away. The following trains are 12 minutes and 18 minutes away.

CharlieChat supports the following Boston MBTA subway services:

Red Line
Orange Line
Green Line
Blue Line