Simplify the following text for a Grade 7 native English-speaking person.
Original: Skype ( , a word-play on type ) is a software application that allows users to make voice calls and chats over the Internet . Calls to other users within the Skype service are free , while calls to both traditional landline telephones and mobile phones can be made for a fee using a debit-based user account system .
Simplified: Skype is a software program that uses the internet to make telephone calls .