Although Voice over Internet Protocol, or VoIP, and Time Division Multiplexing, or TDM, represent two separate telephone technologies, combining the two allows both consumers and telephone companies to save money without sacrificing connectivity.
According to the telephony information website VoIP News, VoIP and TDM are two separate technologies. Voice over Internet Protocol refers to the breaking of voice conversations into data packets for transmission across the Internet. Time Division Multiplexing is a more traditional technology that allows telephone companies to digitize video, voice and data for transmission across standard copper telephone lines.
VoIP TDM Gateways:
Some companies offer VoIP TDM gateway service that facilitates the connection of VoIP calls to parties with traditional wired telephone service. VoIP TDM gateways typically handle all aspects of the connection, including Signaling System Seven, or SS7, call setup.
VoIP TDM allows parties on Voice over IP networks to make and receive calls with parties with traditional telephone service. VoIP TDM can also save local exchange carriers money by converting long distance network traffic to less expensive VoIP transport.