Apps like Skype, WhatsApp, Google Duo, Viber, Facebook Messenger, etc. allow free internet calling, but their functionalities are limited. Typically, you can make calls using such an app only if the receiver also uses it. They don’t allow landline calls, either.Likewise, you will find VoIP service providers that offer free or freemium versions of their internet phone systems. Again, these free versions don’t give you access to many crucial collaborative features. You will have to upgrade to their premium version to enjoy those features. Even the free calls in such free plans may be limited to a certain number of hours.All these free apps and services are suitable only for individual consumers or super-small businesses. Business phone systems like Ringover come at a monthly subscription fee but offer many business-centric features and unlimited calling to worldwide destinations, making it worth every penny you spend.