If you often exceed your monthly call minutes, an option may be to make calls over Wi-Fi. The great thing about making calls over Wi-Fi is that it is not limited to just your mobile phone as it can be done on almost any device such as your tablet and PC/Mac. The additional upside is the higher-fidelity Wi-Fi offers, so the sound quality can be much better than on your call plan! The downside is that if you're on a public network or your home network is not properly secured, your call can be bugged. Read here for more info!
I love technology and how it enhances our lives! Just think, without the Apollo moon missions, we might not have calculators! Imagine!!