Please help question about ipod touch with txtfree with voice app !?

Hi i have a question about the app textfree with voice !! I have it on my ipod touch (4th Gen.) Okay i currently do not know where my ipod touch is i'm going insane looking for it :O but the question is would it still ring (if you were using a cell to call it) like would it only ringggg with WiFi or would it go to the operator without WiFi. I'm asking because i might have lost in my house but im not sure ?! So Would it ring in a location without WiFi ?! Because i'm calling it and IT IS ringing but it might have no volume on it :( So ANYONE thaT HAS this app please answerrr please !!!