i-mode phones have a special i-mode button for the user to access the start menu. There are more than 12,000 official sites and around 100,000 or more unofficial i-mode sites, which are not linked to DoCoMo's i-mode portal page and DoCoMo's billing services. NTT DoCoMo supervises the content and operations of all official i-mode sites, most of which are commercial. These official sites are accessed through DoCoMo's i-mode menu but in many cases official sites can also be accessed from mobile phones by typing the URL or through the use of QR code (a barcode).