Tell her it's not you someone is spoofing your number and that she should block your number. If she keeps getting "your" number calling her when she could easily block it that is on her. I had this happen to me just recently. A lady left a voicemail wanting to know why I called her. I called her right back and explained what spoofing was and told her to either ignore my number or block it. Haven't heard back since.
Oh and other carriers DO have this same issue. Do you honestly think a scammer will limit itself to just Verizon? I seen spoofed numbers that were LANDLINE numbers.