Disadvantages Of The VoIP Phone

• Requires Internet access to make calls outside the local area network (LAN) unless a compatible local 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.
• IP networks, particularly residential Internet connections are easily congested. This can cause poorer voice quality or the call to be dropped completely.
• 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
• Due to the latency induced by protocol overhead they do not work as well on satellite Internet and other high-latency Internet connections.