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.  The phone is the cornerstone for the 2 Step authentication for most security protocols.  Normally the verification its an EMAIl or SMS message, both of which can be contained on your phone.