A long time ago, Apple introduced FaceTime video and audio calls that available on all iOS devices and Macs from the same account, phone calls are still restricted to your iPhone. This can potentially become very annoying if you’re working on your Mac or using your iPad, a phone call comes in, and you’re nowhere near your iPhone.
Right now and with iOS 8, you'll be able to receive and make calls not only from your iPhone, but even on Mac and iPad. Thanks to the new Continuity feature, as long as they’re on the same Wi-Fi network and are signed in to the same iCloud account.
How to make and receive calls on your iPad, iPod touch or Mac using your iPhone: STEP 1: In order to make or receive calls on your iPad, you will have to make sure that your iPhone is nearby, on the same Wi-Fi network, and signed into iCloud and FaceTime with the same Apple ID.
STEP 2: Now go to Settings---> iCloud and check that they’re signed in to the same iCloud account.
STEP 3: Now go back to Settings main menu Scroll down and tap on FaceTime. Ensure that iPhone Cellular Calls is enabled on your iPhone, and iPhone Mobile Calls is enabled on your iPad, and that you’ve logged into the same iCloud account for FaceTime on your iPhone and iPad.
STEP 4: Navigate back to the main Settings screen. Then tap on Wi-Fi, and connect the two devices to the same Wi-Fi network.
That's it. Now you can open contacts from your iPad and tap on the phone number of any contact. On iPad or iPod touch, you can also tap a recent contact in the multitasking screen.
You should see a phone app like that on your iPhone..
You will also see a green banner-like notification on your iPhone, which is an indication that your iPhone is being used for a phone call. If you tap on it, it will launch the Phone app, and you can continue with the call from your iPhone. It will you inform you on the iPad then the call was handed off.
In the same way, you will also be able to receive phone calls on your iPad..
In order to disable this feature, simply follow these steps:
STEP 1: Go to Settings---> FaceTime and then tap on the on/off toggle for iPhone cellular phone calls.