Do you call money for micro-calls?

I heard that there is a software for calling, free of charge, called micro-talk, is this software really free?

A: Microphone is a call tool that can save money, but it is not absolutely free. You can make free calls on wifi, but when your mobile phone goes online, it will consume data traffic. The data traffic is money, it depends on the package you use. For example, some friends have a lot of traffic, and they can't use it every month. It is very suitable to make a phone call with micro-phones, and some friends don't have much traffic. If you use micro-phones to call, you have to deduct the flow of money. We need to see how much traffic is used in the micro-verbs? Fee flow? Which is more cost-effective than the phone bill?

It is said that the microphone call consumption is about 500k per minute. It seems that it is quite a fee, so it is recommended that you use it in the wifi environment.