We have had a couple of these cases where a small business was using a cellular line for business and through social engineering a hacker was able to get access to the phone line and diverted it. Which in turn led to multiple other data breeches within this company’s digital operations.

https://motherboard-vice-com.cdn.ampproject.org/c/s/motherboard.vice.com/amp/en_us/article/gy8bxy/t-mobile-text-warning-phone-hijacking-number-port-out-scam