False Answer Supervision (FAS) refers to VoIP fraud, when A-party is incorrectly billed: billed duration is more than duration of actual telephone conversation. The FAS is usually performed by VoIP wholesalers in their softswitches for randomly selected calls. Adding a small amount of extra billed seconds for many calls means a big revenue for the VoIP wholesaler. Actually it means stealing of money from caller (A-party).
Contents
Implementation of FAS
The FAS fraud can be implemented in a softswitch in many different ways. Here are few of them:
- False billing of A-party without calling B-party. Usually a fake ringback tone, loopback audio or voicemail message is played
- Start of billing before actual answer of B-party
- Extra billing after disconnection of B-party
Detection of FAS
The FAS can be detected and blocked in a softswitch. Common methods are:
- Manual verification of Call Detail Records, listening to voice recordings
- Identification of FAS types and using algorithms to automatically detect the FAS
References
False Answer Supervision Wikipedia(Text) CC BY-SA