Using the mobile phone to get onto the internet using other people’s wireless connection

I have a pocket device or a handheld device which includes a chip that is called wi-fi, i.e. a wireless connection that enables me to get on the internet without paying any fee. Sometimes I do research in the street or in any place, and I find these connections, so my device hooks up with them and I am able to use these networks, but I do not know their source or where they are coming from. I do not need any password to access them. This connection does not affect the network because it is only looking at different web pages without downloading anything from the internet. What is the ruling on this action? Is it permissible or not? Can it be likened to receiving TV signals?.