The Fourth International Conference on Ubiquitous and Future Networks (ICUFN) was held in Phuket from 4 - 6 July 2012. ICUFN has covered all converging aspects of computing, networking and communications from 2009 conference and this ICUFN 2012 will be also a successful and exciting conference covering broad topics on ubiquitous and future network technologies. This year we have received 229 paper submissions electronically from 24 countries in the world. Many of the papers were submitted from the Asia/Pacific region, and also the increasing number of submissions was made from Europe and USA. A rigorous review process has followed in which all papers received two or more independent reviews. After the reviews, we have selected 114 papers for presentation at the conference. The accepted papers were organized into 20 technical sessions, which will be held in 4 parallel tracks. The program covers a variety of topics on wireless and wired communication networking technologies including cognitive radios, wireless sensor networks, broadband wireless communications, future network issues, mobile multimedia networking, and other important technologies. The two greetings are followed by the "ICUFN 2012 Program at a Glance."