VoIP protection cannot be ignored. 5 Solutions to protection problems (1)

VoIP Voice IP) or Internet telephone technology refers to the Communication Service-voice, fax and/or voice and information applications transmitted through the Internet rather than the public exchange Telephone Network (PSTN. The basic steps involved in sending Internet phone calls include converting analog voice signals into digital voice signals and compressing signals into Internet Protocol IP addresses) information packages for transmission over the Internet, the steps at the acceptor are the opposite. Because it runs on the internet, VoIP has a very low telephone cost, and the only fee is PNET. It will become a very common means of transmission in the world of long-distance calls.

Recently, VoIP generally uses the ITG Internet Telephone Gateway)/VoIP gateway to transmit voice over IP addresses. The VoIP gateway has the following connection ports.

◆ FXO external exchange board): It is a two-line connection port directly connected to the PSTN.

◆ FXS external exchange station): it is connected to the terminal device through the RJ-11 receiver plug hole, such as ordinary phone.

◆ Ethernet port: It connects to the PC or xDSL modem through the RJ-45 port.

◆ USB port: it connects to external USB devices, such as card readers, 3g hsdpa cards, and Flash memory.

◆ Power port: it is usually the input port of 12 V external power supply.

Mainstream VoIP supports single/dual-channel FXS, and up to 30 FXS are available on the market. The recently developed VoIP has built-in router and wi-fi connection functions. It can implement wireless connection between VoIP and xDSL through a wireless network, thus enhancing its mobility within the Access Point coverage. In addition, there is also a trend of power supply to POE Ethernet, so that VoIP can be driven without external power.

Figure 1 Typical VoIP Architecture

As these ports are constantly connected to the outside world due to surge events, and these ITE information technology devices are connected to telecommunications networks that need to comply with telecommunications management standards, therefore, you have to use protective devices to protect these ports.

Each country has its own security standards, such as the Telecordia GR1089-Core and UL60950, universal ITU-T K.20/K.21) and China's YD/T993, 950 standards. Different standards require protection devices, technologies, and topologies with different stability states. Through comparison, we found that the protection capabilities that meet the US standards are higher than those that comply with the International Telecommunication Union standards, and higher than those that comply with the Chinese standards. In most cases, most of the test conditions that meet the u. S. Standard protection solutions can basically be set through the ITU-T K.2x standard.

To design the most suitable VoIP protection solution, it is important to know the various surge levels of the protector and the protection voltage. Common surge voltage levels are shown in table 1.