BlackBerry CEO John Chen has written an open letter about the company's upcoming Classic smartphone, saying the guiding principle behind the phone is, "if it ain’t broke don’t fix it."

The Classic, which was previously called the Q20, will include a QWERTY keyboard just like the Q10 released in 2013. It will also have a trackpad and navigation keys like 'Menu' and 'Back' at the top of the keyboard, a return to previous BlackBerry features. 

The Classic will also include a 3.5-inch touchscreen. BlackBerry says it will be released by the end of the year, though it hasn't specified a date.

The device is the second from the Waterloo, Ont- based company in the latter half of 2014 - the Passport was launched at the end of September. 

Chen's letter emphasizes BlackBerry's focus on core features and business users. 

"You don’t reinvent yourself every day; you take what you learned yesterday and sharpen it today," Chen wrote. "We are committed to earning your business – or earning it back, if that’s the case. In the weeks ahead, BlackBerry will be sharing more details about Classic that we think you’ll like."