# Subscription Box in Frontend
Once you have configured extension properly from the backend, whenever your customer visits any out of stock product from the store frontend. They will get an option to subscribe back in stock notification for that particular product via Email or SMS or both as per their convenience from the store frontend.
* **Email Subscription Box:**
* **Mobile Number Subscription Box:**
* **Email & Mobile Number Subscription Box Both:**
* **Success Message:**
Once your customer has successfully opted-in for in-stock notification, they will see and a success message that you have set from the store backend.
* **Error Message (if customer is already Subscribed)**
If the customer is already subscribed for in stock notification, they will see an error message as below.
* **Subscripton Box for Configurable Product**
* **Subscripton Box for Grouped Product**
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