Completely free for 1 month, but make sure you cancel before the months end (within 27 days) so you don't get charged.
Call landlines and mobiles in: Canada, China, Guam, Hong Kong SAR, Puerto Rico, Singapore, Thailand, United States.
Call landlines only in: Andorra, Argentina, Australia, Austria, Belgium, Brazil, Brunei, Bulgaria, Chile, Colombia, Costa Rica, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Guadeloupe, Hungary, Iceland, Indonesia (Jakarta), Ireland, Republic of Ireland, Israel, Italy, Japan, Korea, Latvia, Lithuania, Luxembourg, Malaysia, Malta, Mexico, Morocco, Netherlands, New Zealand, Norway, Panama, Paraguay, Peru, Poland, Portugal, Romania, Russia, Slovakia, Slovenia, South Africa, Spain, Sweden, Switzerland, Taiwan, Turkey, United Kingdom, Venezuela.
*Offer subject to availability. Only one Skype Unlimited World subscription can be claimed per customer. To qualify for the offer, you must have or create a Skype account and provide valid payment details. Your first month is completely free, and unless you cancel your subscription within 27 days from the start of your free trial, your subscription will automatically continue and the current rate will be automatically charged to your credit card at the end of your free trial and every subsequent subscription term.
Thanks to gccmelb on OzBargain