In most cases, he will not be notified automatically. Phone and commissary deposits do not come with an alert that reaches the inmate directly. The money appears in his account, but unless he checks it himself at a kiosk or asks a staff member, he may not know it is there until he tries to make a call.
The most reliable way to let him know is to send him a letter. Write a short note telling him you have added funds and that he should try calling. If you are an InmateAid user, the team can provide a coupon code to send that notification letter on the house. Just reach out to them and ask for one.
If he has any other approved contacts who are already in communication with him by phone, having them pass the message along is another option to get the word to him faster than waiting for a letter to arrive.