IP phone or IP telephony involves the use of an existing, integrated Internet network to interact between two or more business or personal segments. The technology has replaced the previously explored PSTN or public switched telephone network system. Calls made via IP telephony can traverse the established Internet network.
IP phone technology empowers call-making via proprietary protocols such as Session Initiation Protocol and Client Control Protocol. The system could be fitted with software-based Soft-phones or special built-in hardware-empowered devices. With the power of integrated analog telephony adapters, even simple telephones can be reused as IP phones.
The essential elements include:
- A system that integrates the DNS, STUN and DHCP clients.
- Signaling and RTP Stack.
- Audio and video codecs.
- Special user interface.
- Dedicated hardware fitted with a microphone, earphones, keypad, display interface, voice engine, ADC and DAC converters, Ethernet and a battery or some DC source.
It also works along systems fitted within Wi-Fi enabled mobile phones, PDAs and analog telephony adapters. Hardware empowered devices enable customers to use commercial VoIP or voice over Internet protocol providers over existing PSTN telephony.
Today, the technology also accommodates designs that have built-in GSM base stations to gain access to remote areas where low-powered gateway transmitting otherwise becomes impossible.
The IP phone flaunts modern features such as access to:
- Caller ID.
- ID Calling.
- Automatic use of network-based directories.
- Conference calls.
- Call transfer and hold.
- Storing user name/number in systems facilitated by different service providers.
- Weather report analysis.
- Live news.
The IP telephony or call access via VoIP is not without its own set of disadvantages. These include:
- Limited or no use in the absence of a dedicated internet access. The system does not accommodate calls beyond the Local area network or LAN, unless there is an integrated, compatible PBX system in place.
- Total dependency on separate electric connectivity. Unlike the PSTN phones, IP Phones and routers connect only via mains electricity. The system is not empowered to work via power generated from telephone exchanges.
- Easy congestion. These networks, particularly residential internet connectivity, easily succumb to congestion. The result is poor voice quality or a complete call-drop, in the midst of an emergency.
- Lapse in connectivity when exposed to high-latency connectivity. The technology does not empower internet-call connectivity when exposed to latency induced by protocol overhead. The system also fails to function effectively when exposed to satellite internet integration.
- Failure when integrated alongside other digital equipment. This technology becomes redundant when other digital systems are integrated into the adopted phone line. Equipment like digital video recorders and home security systems do not integrate with VoIP.
- Challenging emergency calls. The technology becomes a challenge to surpass an emergency. VoIP uses special IP-addressed phone numbers and not regular public-service NANP phone numbers. Hence, it becomes difficult for a 911 operator to identify the exact geographic location of the given IP address.
- Distorted facilitation when challenged by latency and packet-loss. The Internet connection used by this technology makes the integrated system susceptible to broadband latency, jitter and packet-loss. The result is distorted and garbled communication due to transmission error.
- Exposure to Denial of Service attacks (DoS attack). IP telephony, like other internet integrated networks, is subjected to Denial of Service break-downs if the address used is an public IP id.
It is susceptible to attacks from viruses and hacking. The system uses a technology that is completely dependent on the power of integrated PCs. The resultant processor drain leads to frequent communication-quality loss and system-crash.