Introduction: Security terms in VoIP phone systems are useful only when readers understand which risk each feature actually reduces. A small business evaluating an IPPBX can easily see words such as SRTP, Firewalls, authentication, and anti-theft calling and read them as one broad promise: the system is secure. That shortcut is risky. These terms point to different parts of a voice system, and none of them alone proves zero risk, certified protection, or a tested deployment result. For readers comparing small business PBX solutions or learning from small business telephone wholesale search results, the practical value is not to dismiss security features, but to separate feature presence from security outcome. Security Terms Sit at Different Layers in a VoIP Phone System VoIP security is layered because a phone system does more than pass voice from one handset to another. A call involves signaling, media transport, user credentials, administrator access, network paths, logging, and s...