You can receive calls and texts on your iPad by using the Continuity feature found in iOS 8. First you must have an iPhone and iPad both running iOS 8.0 or later. Make sure you're signed in to iCloud with the same Apple ID on all of your devices, and double check that Bluetooth is enabled on both your iPhone and iPad. Your iPad and iPhone must also be connected to the same Wi-Fi signal to receive cellular calls on your Apple tablet. Once all these requirements are met, you can sign in to FaceTime with the same Apple ID on all of your devices and start receiving calls on your iPad when someone contacts your iPhone.
You can check to make sure that the iPhone Cellular Calls feature is enabled by navigating to Settings > FaceTime.