If you are a citizen of a country that is not listed below you will need a VISA to enter Hungry.  Check with your local Hungarian Consulate for the application details.
 
IEEE Communications Society can provide you with a letter to assist with the VISA process if you meet one of the following conditions.

• You are the Author of a Technical Paper that has been accepted in the conference or a keynote, tutorial or panel speaker.  

• You have registered for the conference with full payment.

To receive a VISA Assistance Letter complete the form at http://www.comsoc.org/bin/visa/index.html
 

Visa free entry
Citizens of the EU/EEA member states and of the following countries may travel to Hungary without a visa and may stay there for a maximum period of 90 during the 6 months from the date of the first entry (if the conditions required for staying are met): Andorra, Argentina, Australia, Brazil, Brunei, Canada, Chile, Costa Rica, Croatia, Guatemala, Holy See, Honduras, Hong Kong (the exemption applies only to holders of a “Hong Kong Special Administrative Region”), Iceland, Israel, Japan, Macao (the exemption applies only to holders of a “Regio Administrativa Especial de Macau” passport), Malaysia, Mexico, Monaco, New Zealand, Nicaragua, Norway, Panama, Paraguay, Salvador, San Marino, Singapore, South Korea, Switzerland, United States of America, Uruguay, Venezuela
15 Jan 2009 from http://www.huembwas.org/Consul/ENG/ConsularAffairs.htm.