I helped my son's teacher pay the phone bill. How can I gently send a message to tell her that I helped her pay the phone bill?

If you want to gently tell your son's teacher that you helped pay the phone bill, you can consider the following ways:

1. Greet politely and mention the name and situation of your son, such as "Hello, I'm XXX's parents. I want you to know that I have paid the phone bill for you. "

2. If you are familiar with the teacher, you can express it kindly, such as "Hello, I am XXX's parents and your good friend. I want you to know that I have paid the phone bill for you. "

If you are unfamiliar with the teacher, you can adopt a more formal tone, such as: "Dear teacher, I am the parent of XXX. I want you to know that I have paid the phone bill for you. "

Either way, you should show your kindness and care, and respect the privacy and wishes of the teacher. If the teacher wants to know more details or express his gratitude, he can communicate further.