Batter must verbally call time?

[BSBAL18]

Had this come up. As i am pretty "relaxed" with 13u games, the coach did complain regarding the opposing batter coming to the plate and just putting his hand up towards me for time, but never "asked for time".

As i have played ball for many'o'years, thats just how we got time as a batter... but is there a RULE that states "just because someone holds up their hand, doenst mean you give them time.... they must verbally ask for it?"

It seemed a stretch for me, but watching MLB and such, i always verbally hear the 3rd basecoach ask for time after a slide from a player, and even batter's i hear them yell "TIME" if they want to step out...

So whats the call? dont call timeout if only the hand is raised and i dont hear a verbal "TIME" ?