This might be a silly question, but if I download Tango, the person that I am calling has to have it installed on their phone too right? I can't call someone who is on Skype from Tango?
You're right. Skype can't correspond with Tango in vice versa. The end user has to have it installed as well. I don't know why Skype isn't working but I would try a un installation and reinstall.