Vo IP Phone - Disadvantages of VoIP Phones

Disadvantages of VoIP Phones

• Requires Internet access to make calls outside the local area network (LAN) unless a compatible local private branch exchange (PBX) is available to handle calls to and from outside lines.
• VoIP phones and the routers depend on mains electricity for power, unlike PSTN phones, which are supplied with power from the telephone exchange. However, this can be mitigated by installing a UPS. The Power over Ethernet interface simplifies this immensely since power can be "injected" at any connector (especially in passive mode where all devices are drawing the same voltage) or at the router. This is a major reason the dominant call center and PBX VoIP systems rely on PoE exclusively)
• IP networks, particularly residential Internet connections are easily congested. This can cause poorer voice quality or the call to be dropped completely. As commercial grade routers begin to incorporate "managed" or "carrier" QoS features, this is less of an issue, but such features typically require expert configuration.
• VoIP phones, like other network devices can be subjected to denial-of-service attacks as well as other attacks especially if the device is given a public IP address; This is especially significant as an issue with wireless devices using 802.11 protocols
• Due to the latency induced by protocol overhead and other factors they do not work as well on satellite Internet, analog cell ("edge" networks) and other high-latency Internet connections. Extremely latency sensitive applications (music, remote device control) as of 2012 simply cannot exploit VoIP protocols.
• Proprietary vendors such as Skype and Google Voice focus on improving call quality between their own users to grow their user base, which to some degree competes and conflicts with the goal of better connections from Skype to Google Voice, or from either to the existing PSTN and cellular networks. The best codecs tend to be proprietary and not licensed to competitors, retarding the growth of the industry and causing incompatibility.