What is Telecommunications Fraud?
… large bill for the customer. Customer Frauds: This technique infiltrates companies who use telecommunications services. Hackers can enter into the phone network via voicemail system, improperly discarded SIM cards and pre-paid calling cards. After infiltration, the fraudster uses the phone system to make unauthorized calls, often to high-cost locations. REDUCING THE RISK OF A TELECOMMUNICATIONS FRAUD LOSS Regularly monitor call activity to detect suspicious patterns. Review phone bills fully to avoid overlooking fraudulent transactions. Change voicemail passwords from default settings and do not use ones that can be easily guessed such as 1-2-3-4 or 0 …
https://www.epicbrokers.com/insights/what-is-telecommunications-fraud/