Call redirection is the rerouting of a phone call to a different number, SIP endpoint, voicemail box, or app handler. In normal telecom use it appears as call forwarding, voicemail transfer, or routing rules in a PBX. In mobile security, the same idea can be abused when malware changes where calls are answered, sent, or displayed so the victim misses verification calls or speaks to an attacker-controlled endpoint.
This matters because voice calls often carry sensitive business and security workflows: delivery coordination, customer support, and one-time verification. Spyware and fraud tools may request telephony permissions, act as the default dialer, or manipulate call settings to intercept or reroute calls. Defenders look for unexpected forwarding changes, strange dialer permissions, and missed-call patterns that do not match user behavior. Strong app provenance checks, permission reviews, and telecom-side controls help prevent abuse.