How can I disable the flip on my Samsung sa-s3600i cell phone so that the calls are connected only when I press the 'answer' button?

With many flip phones, you simply press the up button during a call to increase the volume.

If you need more specific instructions, please specify the model of your Samsung flip phone.

Press volume up and down button that will mute ring

PLease Change your Keypad Ic

Check the settings on your phone to make sure you have chosen to answer calls by clicking the connect button. There are other choices like press any key to answer call that might be interfering with your calls.

s3600 emargency.call.only

Go to MENU, SETTINGS AND TOOLS, SOUNDS SETTINGS, READOUT, then select FLIP OPEN AND TALK, turn it off.

With the phone closed, hold down the multi-function button on the lower-right side of the phone for a few seconds; that will lock all of the buttons on your phone until you either a) open the phone, or b) hold down the same button for another few seconds to unlock the keys.
To the best of my knowledge, there's no way to set the button to ALWAYS be disabled when closed; you have to lock it every time you close the phone.
NOTE: Locking your keys can create another problem, at least on my phone, where I've disabled the option to anser a call by flipping it open (I prefer the option to view the caller and ignore it if it's not a priority). When I receive a call with the phone locked, I have to wait a few seconds after flipping the phone open before pressing the "answer" key; if I answer too soon after flipping it open, the phone tends to lock up for about 30 seconds, which obviously kills the call.

I know it's a flip phone and I am not familiar with this model, but sometimes the <--> button on the side is pressed by accident, this can adjust the volume [*during a call*] up or down.

To the best of my knowledge there is no way to disable the feature...Sorry...