Which is more economical, texting or calling for a minute? How much difference?

It depends on who and where you call or send a message to. If it's a long distance or international call, you'd better send a message. It's more convenient to make a phone call if it's closer, but SMS is definitely economical. M-Zone cards in many places have SMS packages, such as10,200,20,400, which are generally not too late. If you are in love at school, forget it!