This is a method of providing a phone service to people over the Internet. This type of service moves the traditional phone switch off site and allows more than one company to use a particular switch.
Cisco 6921 is inexpensive business class IP phone model supporting video connection (Cisco UC Phone 6921, Standard Handset).
Cisco 6921 IP phone supports up to 2 lines has full-duplex loudspeaker, supports call holding on each line, hold, transfer, conference keys, tricolor indication of line condition, functional keys for simplified use of IP phone functions.