This is not a good idea.

Spam calls are, by and large, automated. When the number does not answer several times in a row, the number is often auto deleted from the list so as to get more scams done.

When you answer, it confirms for the automated program making the calls that your number is still in service and is answered.

I used to do this, but I stop answer. Now I just wait to they hang up (I silence the phone using the lower volume button) and next I do block the number. If you answer or hang up, they'll continue calling you.