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NEC i-series Gateway
Voice signal compression may be used to reduce the bandwidth
requirements for the signal between the units. The choices for voice compression are: G711 (64 K), ADPCM 32 (32.), ADPCM 24 (24 K) and G729a (8 K). ADPCM stands for Adaptive Pulse Code Modulation and is defined in G726. There is a trade-off that must be made between voice compression and voice quality. The more the signal is compressed, the poorer the voice quality when it is received.
There are three connectors on the back of the i-Series Gateway: 2 DB25 WAN connectors and one RJ45 10BaseT Ethernet (IP) connector. These may be used to connect to multiple remote locations or to multiple data links to the same location for back-up purposes. The i-Series Gateway is available with eight or twelve ports to support eight or twelve i-Series telephone connections. The i-Series Extender is connected to the i-Series telephones at the remote site. It restores the data received to a format that can be understood by the i-Series telephone. In addition to that, it provides power to the telephones. Two Extender versions are available.
The i-Series Branch Extender which is available with eight or twelve ports and the i-Series Single IP Adapter with a single port. The i-Series Branch Extender has three connectors on the back for connecting to WAN or LAN just like the Gateway. This unit can also supports local telephone access with an optional local trunk circuit. This local trunk appears on any selected key on the i-Series telephone. The trunk circuit supports both incoming and outgoing calls. Incoming calls will ring at designated local telephones. The i-Series Single IP Adapter is a single port device that can only connect to an IP network. It has connecters on the back for the network, a PC computer and an i-Series telephone. Each of the units can be programmed from an i-Series telephone or from a computer. The built-in Management Interface (MI) software can be accessed using a terminal emulator, Telnet or an Internet browser. There is no special software required on the computer to configure these units. From within the Management Interface, it is also possible to use the network connection to log into a remote Extender to change the configuration.