Yes, you now have the facility to call using Wi-Fi using iPhone, (if your mobile network provider allows it). It is very similar to making calls on VOIP. There is no extra expense, accounts or apps involved. You only need three things: iPhone with IOS8, Wi-Fi, and a service provider that allows making this call. 

What is Wi-Fi calling?

Wi-Fi calling is a network provider driven calling unlike face time calling, which depends on SIP/IMS technology. To make or receive calls using Wi-Fi. The quality of voice is very crisp.

How to allow Wi-Fi calling on your phone:

Go to Settings
Once you are in settings tap on Phone
You will see an option of ‘calls’, under that tap Wi-Fi calls
Once you are there enable Wi-Fi calls
And say OK

Currently, only two network providers allow this facility T-Mobile (US) and EE (UK). The facilities will soon be available to other network providers also. The calls will be made normally. The basic disparity between a regular call and a Wi-Fi call would be that your network would show ‘T-Mobile Wi-Fi.’ But sadly the Wi-Fi calling is not available on iPhone 5 by T-Mobile.

Remember, if you are having trouble with making calls using Wi-Fi, make sure you check the service provider service first. Check if it is providing a Wi-Fi calling option or not.

Thus, you can make calls or receive calls using Wi-Fi, without interruption and clarity, as compared to the regular carrier. That’s it. It is important to have a proper knowledge of steps to use Wi-Fi Calling with iOS 8 or how to enable Wi-Fi Calling with iOS 8.