Final answer:
Power over Ethernet (PoE) is the technology that supports IP telephony devices without the need for external power. VPN, QoS, and WEP are unrelated to providing power to devices.
Step-by-step explanation:
The technology that supports IP telephony devices without requiring external power is Power over Ethernet (PoE). PoE allows both power and data to be carried over a single Ethernet cable, making it possible to power devices like IP phones, security cameras, and wireless access points without the need for a separate power source.
VPN, QoS, and WEP are not technologies used for powering devices. VPN (Virtual Private Network) provides secure access to a private network over the internet. QoS (Quality of Service) is a set of technologies used to manage network traffic and ensure the performance of critical applications. WEP (Wired Equivalent Privacy) is an outdated security protocol for wireless networks.