Echo Cancellation

The IP•Tube GT1-Ecan encapsulates full and fractional T1 circuits into IP packets. T1 Over IP connections provide for the interconnection of Channel Banks, PBXs and Telecom Switches via LANs, WANs, MANs, Satellite and Wireless Ethernet.

The IP•Tube GT1-Ecan ships with four T1 interfaces with Echo Cancellation and two 10/100 BaseT Ethernet Interfaces. 

Echo Canceller
The IP•Tube GT1-Ecan has four independent integrated T1 Echo Cancellers that cancel up to 64 milliseconds of Far End echo.  The Echo Canceller DSP detects and cancels echo at the far end so that the interconnecting packet’s network delay and jitter has no impact on echo. The echo canceller meets ITU-T G.164, G.165 and ITU-T G.168 requirements for echo cancellation.

Echo is one of the most important factors that affects voice quality. The primary source of echo is the impedance mismatch at the hybrid that links a 2-wire analog loop to a 4-wire digital trunk. Echo Cancellation is essential for T1 circuit emulation that involves voice connections to the PSTN and delay in excess of 20 milliseconds. Packet networks that traverse an intranet or internet backbone can easily exceed 20 milliseconds. The IP•Tube's Echo Cancellation provides the elasticity to support high quality voice connections across networks with significant delay and packet jitter.

The primary purpose to employ T1 Circuit Over Packet technology is to reduce or ideally eliminate the T1 leased circuit charges.  For an enterprise utilizing their existing intranet is very compelling. Typically these intranets are already handling a very demanding load with significant packet jitter.  The IP•Tube Echo Cancellation has jitter buffering greater than 100 milliseconds which is more than enough for the majority intranets and beyond the signaling delay tolerance of Voice PBX or Switch.

Choosing Wireless Ethernet for the transport of T1 Circuit Emulation is very popular since the circuit lease charges are eliminated.  Commercial Off the Shelf Wireless Ethernet radios do not perform well with full duplex T1 circuit emulation packet traffic that is configured to keep the round trip less than 20 milliseconds.  The IP•Tube's Echo Cancellation has the elasticity (Jitter Buffering and reduced Packet Frequency) to support the use of Wireless Ethernet for T1 Circuit Emulation.

Transparent Interconnect
The IP•Tube GT1-Ecan’s transparent operation maintains the proprietary signaling required to support PBX features such as call conferences, call forwarding, caller ID and SS7.

Signaling Support
Robbed Bit, PRI ISDN, SS7, and Proprietary out of band are supported. Echo cancellation is automatically disabled during FAX and Modem communications. Transparent support for Modem or Fax. Voice quality is not compromised.

Legacy phone equipment investment is preserved.

IP•Tube GT1-Ecan Standard Features

Dual LAN Interfaces
All IP•Tube GT1-Ecan models ship with dual 10/100BaseT Ethernet LAN ports. The dual Ethernet interfaces provide for:

• Management interface on LAN port 2 when LAN port 1 is connected to a VPN tunnel
• Alternator Option for load balanced interconnects
• Protector Option for Redundant Packet Path connections with Constant or Switch Over Criteria

Assured Delivery Protocol
In order to assure high quality communications over links with intermittent or noisy performance, such as Wireless Ethernet. The IP•Tube GT1-Ecan employs Engage’s robust Assured Delivery Protocol with the following benefits:

• Packet out of sequence detection and re-sequencing
• Lost packet retransmission with configured delay

IP•Tube GT1-Ecan OPTIONS

Protector OPTION -PRO
The Protector option provides for automatic protection of the T1 circuit over independent IP packet routes. After conversion of the T1 circuit into IP packets, two identical packet streams are created. These duplicate packet streams are used to provide redundant IP connectivity to the remote location in either “Always-On” or “On-Demand” switch over modes.

The need to Protect Critical Communications is in high demand for the following applications:

• Public Safety Network Redundancy for Police, Fire and Medical
• Auto Recovery for Military Communication
• Delivering on Service Level Agreements
• Resilient Cellular Backhaul

Always-On
In “Always-On mode, the Protector sends two identical packet streams simultaneously on the LAN1 and LAN2 ports of the local IP•Tube GT1-Ecan-Pro. The remote unit monitors both LAN1 and LAN2 incoming traffic and on a packet by packet basis selects the best packet to use for conversion from IP back to T1. In most cases, switching of the receive packet source between LAN1 and LAN2 can be done without T1 circuit interruption

Lossless Data Compression Option -C

The IP•Tube GT1-Ecan continuously detects idle and redundant data within each T1 Voice circuit resulting in as much as a 56 to 1 bandwidth savings.
TDM over IP WAN bandwidth is not consumed by silent or redundant circuits.
Note: Compression only supported with IP•Tube GT1-Ecan-C models.

Rack Mount Kit

Far End Echo Cancelling

IP•Tube GT1-Ecan utilizes Digital Signal Processors that detect and cancel echo at the far end so that the packet network delay has no impact on echo. The echo canceller samples the voice signal, estimates and removes the echo, leaving the original speech. The linear digital signal processor (DSP) models the echo and performs the main echo cancellation task. A non-linear DSP processor is then optimally employed to subtract out any residual echo or reflected noise components.
Echo is one of the most important factors that affects voice quality. The presence of echo depends on both echo level and echo delay. The primary source of echo is the impedance mismatch at the hybrid that links a 2-wire analog loop to a 4-wire digital trunk. The hybrid is not completely efficient in carrying the electrical energy and a certain amount of the electrical energy, or voice signal, is reflected back and may be perceived as echo.

Occasionally, acoustic feedback of certain phones also causes noticeable echoes. These sources of echo are able to be cancelled by the human brain as long as the time between our speech and the echoed speech is not greater than 32 milliseconds.

Engage's T1 Over IP products have a minimum delay configuration, 1 millisecond packetization and 4 packet buffering, which introduces a delay of 5 milliseconds. The amount of delay introduced by the packet network depends upon its switching times, packet processing, packet jitter, transmission, loading and quality of service configuration.

For example a network connection that utilizes Gigabit Ethernet switches, which introduce delays in the microseconds, does not require echo cancellation. Wide Area Networks that traverse an intranet or internet backbone have varying degrees of delay which can easily exceed 28 milliseconds. Total round trip delays in excess of 32 millisecond makes echo perceptible.
The IPTube’s Echo Cancellation provides the elasticity to support clear connections across networks with significant delay and packet jitter.

T1 Private Line Services over IP

The IP•Tube GT1-Ecan provides enterprises with the ability to interconnect their existing phone systems over flexible bandwidth lines that are used to carry data, voice, and video. The Voice Only Leased Line Toll charges assessed by long distance and local carriers are eliminated or dramatically reduced by transporting voice traffic across LANs and WANs.

LANs
The most compelling option for the interconnection of T1 based systems is when it can be accomplished over a Local Area Network. The deployment of Fiber based LANS such as FDDI and Gigabit Ethernet, provides organizations with high performance and high quality bandwidth that is especially well suited for the interconnection of PBXs and Telecom Switches.