The Cisco 2-port Network Interface Module - FXO (Universal) (NIM-2FXO) is a device that allows you to connect your Cisco router or switch to a traditional phone line. The module is compatibile with Cisco's 4331 and 4351-X ISRs (Integrated Services Routers). It has two analogue ports, each of which can be used to connect a phone line to the router or switch which allows your Cisco device to make and receive phone calls over the public switched telephone network (PSTN).
The NIM-2FXO is designed to be compatible with a wide range of Cisco devices, including routers, switches, and voice gateways. It supports a variety of signalling protocols, including FXO, FXS, and E&M, that enables it to be used with different types of phone lines and phone systems.
The NIM-2FXO also includes features such as Call Waiting, Call Transfer, and three-way conferencing, making it a versatile and useful addition to any phone system.
The NIM-2FXO supports echo cancellation, which means that it can reduce or eliminate echo in phone calls made through the FXO ports. Acoustic shock protection is a feature that can be found on some NIM-2FXO devices. It helps to protect against sudden loud noises or sounds that may occur on the telephone line, such as loud beeps or clicks.