Spent a day acclimating Lexi to tone on the collar.
Although I hardly ever use treats since she was nervous over the sound, to get her comfortable with it I would tone her and give a treat.
Did it repeatedly for 5 minutes, or so until she was relaxed and expectant every time she heard it. Once she got relaxed let her walk away then tone her, give "here" command.
When she came would treat, and praise simultaneously.
Spent rest of day recalling sporadically outside.
Her tone recall was set.