Does a divorce take effect after the husband said to his wife: "You are triply divorced if you speak and do not hang up immediately," and she did not speak and did not hang up the phone for a few seconds, then hung up after the husband reminded her again with the word "immediately"?

As long as the wife obeyed and only delayed a few seconds, you were truthful in your oath and did not break it. If she delayed because she did not hear you say "immediately," the preponderant opinion is that the oath is not broken. Therefore, your divorce did not occur. We alert you that the permissible oath is by Allah Almighty. As for swearing by divorce, it is among the oaths of the wicked and can lead to dire consequences, especially if it is with the wording of "triple divorce," for most scholars consider it to effect a triple divorce upon breaking the oath.