Is there much success with using hand callers to call in feral hogs?

I see a number of callers for hogs both grunting and squealing distress calls on the market but have to question if they work as well as they say they do. I tried to search through the forum and didn't really see any posts about anyone using calls.

If they are effective, is there a certain kind that does the trick? I deer hunt most of the time and have managed to see hogs once or twice but the evidence that they are there is overwhelming.

If anyone has any experience with calling hogs with mouth calls or electronic ones please let me know.

I have a Primos Hog Grunt.
I have used it a few times, and it has not yet brought anything to me.
But there may have not been any hogs in the area at that time. I'll keep using it until I am convinced it doesn't work.
Technique could be a major factor too! Maybe I'm doing it wrong!

I did come across one article on the net that talked about the grunt callers did not work very effectively and more often then not just scared the things off. It did also mention that distress callers had a little bit of success bringing them in to at least investigate what is going on. But it is nothing I have tested out and was hoping someone here maybe had some more insight into the matter.

one of the best hog calls I ever used was "get a round for these lovely ladies" also check out the restrooms, lots of good phone numbers there too.

*Bump*

Have not had much luck with them. But, the piglet in distress call is like crack for yotes!

I have used a varmint call ( rabbet squiler ) to call javelina in. It work if they had piglets with them. They would come boiling out of the brush.