Customer will get auto(real-time) notification on the product page if someone places a new bid.
For this real-time feature, we have used very cost-effective "Pusher" 3rd party service. You need to make an account on pusher.com for this feature.
To send SMS, you need to purchase convenient SMS sender gateway based on your location. We will do free customization to send SMS via your selected SMS sender API. If you are not aware for SMS sender gateway, we will help you for that.