NEVER give your personal info, especially your phone number, on a website forum. This site is not affiliated with any collection agency. The only ones interested in it here are low life scum trolling self-help websites to see how effectively their scams are working.
As ridiculous as it sounds, any response, including blowing a horn into the phone, only encourages them, and may supply them with all the info they need to steal your identity. Never answer a number you don't recognize.