Have you ever received one of those phone calls???
I just did, and guess what? I disconnected the line. Guess what else? They haven't called back. I detest market researchers!!!!! (Their number is still on my incoming phone call screen! -- I may or may not try to call the number back later to see who the devil it was who was so rude as to not even announce themselves &/or the party that was placing the call. If it was the President, I am really sorry I did not "Hold".)
This is a really big bugaboo with me. If I place a call incorrectly/inadvertently, I ALWAYS identify myself & make a comment such as, "I'm sorry, I hit the wrong number" -- or, I'll leave a message (in case of a voice-mail answering server), stating the reason for my call. I never ... repeat, absolutely never hang up or leave some obscure message that might still leave the "callee" in doubt.
I expect the same treatment from those who happen to catch my number inadvertently. I expect that they will stay on the line long enough for me to try & assist them in reaching the party they were trying to reach in the first place. (Perhaps they simply hit a wrong digit. ... Perhaps they had mis-transcribed the number given to them. ... Perhaps the person they were trying to reach had intentionally given them an incorrect number, albeit mine.) Whatever the reason they reached me, I would like to try & assist them.
It's quite difficult -- indeed, nigh onto impossible -- to assist someone who hangs up on you.