time division multiplexing over IP (TDMoIP)
Time Division Multiplexing over IP (TDMoIP) is a migration technique to open up existing TDM techniques to all-IP networks. TDMoIP, time division multiplexing using the IP protocol, takes advantage of IP-based transport networks in metro and long-distance areas without having to replace TDM exchanges and PBXs with new VoIP systems. Restrictions in terms of quality of service( QoS) or performance characteristics are avoided by TDMoIP.
The principle of TDMoIP
In principle, with TDMoIP the voice data is not packaged in data packets as with VoIP, but remains in the TDM data stream. Only at the transition to the IP network does a so-called TDMoIP gateway break down the synchronous bit stream into data packets, add the IP header and transfer them to the IP network. A second gateway restores the original bitstream on the receiving side by removing the overhead, reassembling the contents of the individual data packets, and regenerating the clock.
TDMoIP supports the common protocols for video applications as well as all data transmission protocolsincluding SNA architecture, X.25, Frame Relay( FR), ATM and ISDN. In addition, T1/ E1 and T3/ E3 leased lines can be implemented over IP. For voice applications, the protocols and signaling data including ISDN, SS#7 and Q-Interface Signalling Protocol( QSIG) are transmitted completely transparently.
The different variants of TDMoIP
There are several TDMoIP variants. These include TDMoIP( CE) and( CV), which stands for Circuit Emulation and Compressed Vioce, ISDNoIP and DECToIP.
TDMoIP (CE) emulates circuit-switched services such as T1/E1, T3/E3 over IP networks, Ethernet and MPLS. This technology is suitable for such applications that require low delay and highest quality for transporting voice and video over IP protocol. The CE variant guarantees continuous data transport and quality of service (QoS).
The CV variant of TDMoIP is designed for the transport of compressed voice. It is used wherever the available bandwidth is limited. The voice compression reaches up to a data rate of 4 kbit/s. This variant is comparable to Internet telephony (VoIP), but can transmit signaling information transparently. TDMoIP (CV) is ideal for voice transmissions in WLANs, via cable modems and via Powerline.