Answer supervision

Has anyone run into a problem with answer supervision and knows how to correct the problem of asterisk not recognizing it when a call does not have it

for answer supervision, normally it use polarity reversal. if asterisk don’t recognize, normally it is for your lines don’t provide ploarity reversal signal. you could use voltage meter to test it from our knoeledge base ,and I am sure that you can solve your problem through this way.The title is "How to measure the FXS port’s Polarity reversal function?"