Mobile applications that do not rely on an internet connection to make calls[4] are immune to such attacks.[why?]
In some cases, Chinese manufacturers[citation needed] are using default passwords that lead to vulnerabilities.
[5] While VoIP is relatively secure[citation needed], it still needs a source of internet, which is often a Wi-Fi network, making VoIP subject to Wi-Fi vulnerabilities[6][further explanation needed] Since VoIP runs over an internet connection, via wired, Wi-Fi or 4G, it is susceptible to packet loss which affects the ability to make and receive calls or makes the calls hard to hear.
Using the extensions provided by VoIP PBX capabilities, the spammer can harass their target from different numbers.
[citation needed] The process can be automated and can fill the target's voice mail with notifications.
], allowing a caller to pose as a relative or colleague in order to extract information, money or benefits from the target.