This happened in Pakistan, where a Chinese manufacturer used the same IMEI number on thousands of cell phones of a particularly cheap model (The model was cloned from a Nokia phone and cloned its IMEI # as well). One day in July 2008, one customer had his cellphone stolen and reported it to Pakistan Telcom Authority, who promptly banned that device using its IMEI number. Result: Mayhem for other owners who owned the same model of phone, as they were all banned at the same time. There were unhappy customers storming dozens of mobile phone stores and sales of Chinese-made phones came to a complete stop for a few days.
An archive of the mayhem that ensued is still saved here: http://www.asiamedia.ucla.edu/article-southasia.asp?parentid=94421