BT, the company once known as British Telecom, said on Monday that it is now exclusively negotiating a possible £12.5 billion ($19.6 billion) takeover of the mobile carrier EE, a joint venture of Germany’s Deutsche Telekom and France’s Orange. BT and EE are now in a period of exclusivity that will last for “several weeks”, during which time BT will “complete its due diligence and for negotiations on a definitive agreement to be concluded.”