can i answer without slide ?

The Umidigi A3 Pro seems to have  strange ways to answer calls and sliding seems unavoidable in the stripped down Android version it has.

If you get an incoming call when the screen is locked, swipe up smoothly and relatively slowly in the area to the left of the bouncing green dot. Unlike with other phones I've had, If you try to flick rather than swipe, it doesn't work on the Umidigi. it takes few practice sessions varying the swipe speed until it becomes more comfortable. Swiping too quickly or too slowly doesn't work.

An second answer method is to swipe down to the left of the top notch as if you are bring down the standard pull-down menu. You will see two options to press: one is to answer the call and one is to reject the call.

Hope this helps.