There are no universal rules which govern the use of wireless microphone equipment globally. The rules and regulations regarding which frequencies are allowed for wireless microphones vary widely by country.
We can provide information regarding rules and regulations for the UK, however because rules and regulations vary from country to country, we cannot advise which frequencies to use outside of the UK. Unfortunately there is no universal database that contains all this information.
For information about the rules and regulations for a specific country it is recommended that you contact the Sennheiser subsidiary or partner company in the country in question.
You can find information regarding frequencies abroud here: http://en-uk.sennheiser.com/service-support-sifa
You can find contact details for these subsidiaries and partner companies here: http://en-uk.sennheiser.com/about-sennheiser-at-a-glance-sennheiser-worldwide