"I only communicate thru OfferUp messenger so please don't give me your contact info and don't ask for mine!"
If they ask for my number or give me mine, I tell them to refer to the second paragraph of my ad or simply "I rather communicate via OfferUp messenger". I do not give out my number for several reasons. Other to guard my identity (to ward hackers), but I generally get very annoyed with pointless phone calls when text messages are sufficient enough, especially for this app. Giving out my phone number creates unnecessary annoyance plus back and forth conversations without any fruit (this has happened to me several months ago when I was dumb enough to give out my phone number). I canceled the sale because he was very indecisive with his decision plus he kept calling my phone and sending a FaceTime requests when I told him to just text me. Even those that may not be hackers or scammer cannot respect my rules or OfferUp rules. Yesterday, I canceled a sale with some kid because he wanted to trade sneakers and asked for my number. Mind you that I advise those that want to trade to have thier sneakers posted on thier OfferUp up page and I am not doing business offline. I told him that since he can't follow the rules and did not read my ad, I'm no longer interested in trading and I blocked/reported him.