Knock, knock - is anybody there? The next time you try to unlock your LG G2 or G Flex, you may have to knock a few times before it will open. LG announced that it will add the Knock Code security feature to the two handsets this April.

LG first introduced the Knock Code feature at Mobile World Congress earlier this year with the LG G2 Pro smartphone. The company subsequently added the feature to the G2 Mini, F Series and L Series smartphones. Now, the company seems intent on releasing this feature on many of its smartphones.

The Knock Code functions exactly like the traditional passcode or dot pattern used on other devices, but LG says it offers a lot more options and is, therefore, more secure. Smartphones with the Knock Code feature built into their software divide the screen into four quadrants. The user then chooses a pattern of 2 to 8 taps in the different sections. LG says that there are over 800,000 different combinations, making smartphones with Knock Code extremely secure.

LG is marketing Knock Code as the ultimate secret hand shake between you and your smartphone. If you have no rhythm, don't worry - Knock Code will unlock your smartphone based on the number of taps, not the frequency or beat with which you tap.

"LG engineers placed a great amount of emphasis on providing users with exceptional security and convenience when developing Knock Code," CEO Dr. Jong-seok Park said in a statement. "Making Knock Code accessible to a wider audience is consistent with our direction to differentiate LG mobile devices on the basis of user experience."

LG claims that it is much harder to memorize some one's Knock Code than it is to memorize someone's passcode or dot pattern. LG also argues that Knock Code offers "a level of security far greater than other devices, even those with fingerprint-recognition systems," but did not back up its claims. Still, Knock Code is undoubtedly a different take on the same old smartphone security debate.

The Knock Code feature also offers the cool KnockON feature, which allows users to simply knock on their smartphone display to wake it up and see what time it is, if they have any updates, etc. KnockON offers faster and easier smartphone access. It is also quite intuitive, sort of like the Clapper. Knock on. Knock off.

The new Knock Code feature will be available on the LG G2 and the G Flex sometime in April as a firmware update.