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Cellular Backhaul

7” (L) x 5.5” (W) x 1.50” (H)
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IP•Tube G4 T1

Cellular Backhaul

IP•Tube G4 T1

Cellular Backhaul

Enable One to Four T1 interfaces for T1 over IP Voice and Data 

IP Tube G4 T1 Product Image


7” (L) x 5.5” (W) x 1.50” (H)


The IPTube G4 T1 is available with one to four T1 interfaces and single 10/100 BaseT Full/Half Duplex Ethernet Interfaces. An optional integrated 5 port QOS/VLAN/Rate Limiting Layer-2 Ethernet switch is available.

An Ethernet Switch Option provides transparent LAN bridging, user data bandwidth and access control through rate limiting and port-based VLAN filtering and tagging. The T1 interfaces have configurations that for provide independent protocol, compression, packet sizing, buffering, framing, coding and channel settings. Enable additional T1 Ports as needs expand using a software-based license key. The protocols supported are IPTube, CESoIP, and HDLCoIP.

Transparent Interconnect

The IPTube G4 T1's transparent operation maintains the proprietary signaling required to support PBX features such as call conferencing, call forwarding, caller ID and SS7. Legacy phone equipment investment is preserved. Transparent support for Modem, Fax, or Data circuits. Voice quality is not compromised.

PBX G4 to G4 4-Port Diagram

IP•Tube G4 T1 Standard Features

Assured Delivery Protocol

In order to assure high quality communications over links with intermittent or noisy performance, such as Wireless or Broadband over Power Line, the IPTube G4 T1 employs Engage’s robust Assured Delivery Protocol with the following benefits:

  • Packet out of sequence detection and re-sequencing
  • Duplicate skipping
  • Lost packet retransmissions with configured delay

Dynamic Host Configuration Protocol - DHCP

All IPTube G4 T1 can be configured to obtain its Internet Protocol network parameters: IP Address, Subnet Mask, Default Gateway, DNS; from a local DHCP server.

Domain Name Addressing

The IPTube G4 T1 can be configured to use a Domain Name for the remote IPTube in place of a fixed IP address. Supports mobile multi service provider installations with ease.

Dynamic DNS

IPTubes can be configured to register their IP address with Dynamic Domain Name Servers for discovery by the IPTube at the other end of the T1 circuit. DDNS support combined with DHCP make installations Name-based which is very easy to setup and maintain when compared to Static IP addressing.

Secure Socket Shell - SSH

Engage’s Secure Socket Shell, which is based upon industry proven Open SSH and FIPS 140 approved Open SSL version 2.0, provides secure encrypted communications between SSH clients such as OpenSSH, SecureCRT, and PuTTY and the IPTube's Command Line Interface.


The IPTube G4 T1 is able to be fully managed with SNMP via standard and private MIBs. Large scale deployments of IPTubes with centralized management have made SNMP support a priority. SNMP Traps for error events enable proactive service fault isolation.

Full T1 Connection Across Two ADSL Lines

The IPTube G4 T1's two Ethernet interfaces are able utilize two ADSL Ethernet Modems, that have opposite high speed direction, to transport a T1's symmetrical bandwidth.

Service Quality Packet Prioritizing

The IPTube G4 T1 uses the Type of Service byte in the IP packets to prioritize the encapsulated T1 frames. The setting of the TOS byte can be used to ensure that the real time TDM data from the IPTube G4 T1 is ensured high priority.

VPN Network Management

Interconnecting the IPTube G4 T1 through a Virtual Private Network with a sufficient real time committed information rate ensures that the required quality of service is provisioned. TheIPTube G4 T1's second LAN interface, which requires the Switch Option, provides a management port when the LAN1 interface is connected to a VPN. Each Ethernet LAN interface features independent IP network configurations.

IP•Tube G4 T1 Optional Features

Ethernet Switch OPTION - SWITCH

The IPTube G4 T1 is available with a five port 10/100 Ethernet QoS switch integrating a high-performance switching fabric with four priority queues. Advanced features include 802.1p/IPv4/IPv6 traffic classification, full IEEE 802.1Q VLAN, RMON, SNMP, Port Monitoring and Layer 2 firewall. 

QoS determined by destination MAC address, port ID, IEEE 802.1p and multimedia traffic tags, IPv4 Type of Service (TOS), and Differentiated Services (DiffServ).

Rate Limiter

The Ethernet switch Ingress and/or Egress Rate Limiter option enables the reservation of the bandwidth for time-sensitive T1 Over IP real time connections. Required for applications where the LAN traffic can exceed the WAN bandwidth required by the T1 over IP/Ethernet application. The data rate limit range is 128 kilobits to 64 Megabits in binary increments.

The Rate Limiter option limits the WAN bandwidth utilized by the LAN1 to LAN2 bridge. Rate Limiting the traffic enables the reservation of the WAN bandwidth for time the sensitive T1 Over IP real time connections. Great for Wireless WAN T1 applications. Rate Governing is only applied in the direction to the WAN to minimize latency. 

Rate Limiter Diagram

Virtual Private Network Support

Interconnecting the IPTube G4 T1 through a Virtual Private Network with sufficient real time committed information rate ensures that the required quality of service is provisioned. The second Ethernet interface provides a management port. Each LAN interface features independent IP network configurations.

Lossless Data Compression Option

The IPTube G4 T1 detects idle/redundant data within each DS0 resulting in as much as 56 to 1 bandwidth savings. T1 over IP bandwidth is not consumed by silent or redundant circuits. Management of the IPTube G4 T1 is accomplished with a Command Line Interface that is accessed through a Console or Telnet connection. Common templates provide for cut and Paste configuration.

Alternator Load Balancing Option

The IPTube G4 T1-ALT Alternator option alternatively sends the IP packetized T1 frames on LAN 1 and LAN 2. The Alternator option enables fractional and full T1 circuits to be split over two IP WAN connections such as xDSL. The Lossless Data Compression option can be combined with the Alternator option to minimize the bandwidth required from the alternative paths. The cost of interconnecting T1 communication systems across packetized xDSL is a fraction of long distance leased T1 circuit costs.

SuperTube Option

Engage Communication super sizes IPTube T1 Circuit extension over Ethernet Packet networks.  The Engage SuperTube option combines four T1 circuits into one IP packet stream.  The SuperTube is designed to support Cellular Backhaul’s tight latency requirements when multiple T1 circuit interconnects are to be extended over Packet networks.

SuperTube T1 Over IP Diagram

The typical way to extend T1 circuits across packet networks is for each T1 to be encapsulated into individual IP packet streams.  The SuperTube Sized IPTube reduces the encapsulation overhead bandwidth and the packet frequency by 75%.  The reduction of packet frequency enables network processors that are pressed with the low latency packet processing.

Cellular Backhaul has latency requirements that can be as stringent as four milliseconds.  In order to rate adapt the clock and to take into account the jitter of the Ethernet buffering of the circuit extended packets is required.  The frequency of the packets may need to be as low as 250 micro seconds to meet the latency and buffering requirements. 

The packet processing for 4 bidirectional T1 circuits at 250 microseconds packet interval full duplex is 32,000 packets per second.  32,000 packets per second full duplex is not something that 802.xx and WiMax wireless radios are able to reliably process.   The SuperTube option cuts the packet processing requirement to 8,0000 packets per second which can be handled with ease by commercial grade 802.xx and WMax radios.

Protector Option

The protector option utilizes the second LAN interface as a redundant path for the interconnection of the IP encapsulated T1 Circuit. The extension of the T1 circuit has a fault tolerant link that is configured to always on, or with switch over criteria.

Protector Option Diagram

Protector Option -EnPRO

The Enhanced version has configuration parameters that enable a secondary packet path with high relative delay to primary path be synchronized. The packet sequence delay synchronization ensures concurrent redundancy with a high degree of error tolerance. Error free operation is accomplished when a primary or secondary Packet is not received and a redundant duplicate packet is available. The IPTube also supports the transmission of multiple duplicate packets to support Mission Critical Circuit extension with redundancy that is only limited by the bandwidth provisioned.


The GPSDO Option receives GPS satellite timing signals to control an onboard oscillator providing from a T1 Stratum 1 reference clock. The GPSDO Option utilizes a mixed-signal phase lock loop GPS driven frequency module to generate extremely accurate 1.544MHz T1 references clocks that are frequency locked to the Global Stratum 1 source. The Stratum 1 clock is the basis for all telecom voice and data interfaces, required to assure proper synchronization of signals and call quality.

Pay-As-You-Grow Field Upgrades

The IPTube G4 T1 is designed for Pay-As-You-Go growth from 1 T1 through 4 T1s per IPTube G4 T1. Customers can elect to economize initial network installations, by purchasing their IPTube G4 T1 with a single active T1 port. As the network grows enable additional T1 Ports via a software-based license key. Field upgrade benefits are extended to our Industry-Best Lossless Data Compression. Just as T1 ports are field upgradeable, so is Lossless Data Compression. At any time, each T1 port on theIPTube G4 T1 can be upgraded to Lossless Data Compression with a simple software-based license key installation. If upon installation, you determine that your IPTube G4 T1s are best deployed with Lossless Data Compression, you're still in business with the per port field upgrade!


T1 Over IP Ethernet Benefits

  • Transparent leased and private line services over less expensive IP and Ethernet networks
  • Protects investment in traditional telephony and TDM equipment
  • Disaster recovery for T1 circuits with 1+1 and 1:1 redundancy.
  • Operating expenses are minimized by leveraging the efficiencies and ubiquity of IP, Ethernet and MPLS
  • Ethernet, IP and MPLS infrastructures are inexpensive, fast to provision and scalable.
  • Easy installation with IP-based management and  carrier grade diagnostics.


T1 Private Line Services over IP

Multi-Site Enterprises, Cellular Service Providers, Education Districts, Universities, National, State and Local Government, and Municipalities incur significant recurring monthly costs for rigid-bandwidth leased lines used only for the interconnection of PBXs and Telecom switches.

The IPTube G4 T1 provides organizations 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.


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 Gigabit Ethernet, provides organizations with high performance and high quality bandwidth that is especially well suited for the interconnection of PBXs and Telecom Switches. 


Wide Area Networks that have sufficient bandwidth and Quality of Service provisioning result in very significant cost savings especially for Multinational Corporations. The IPTube DLT1-C with loss less data compression, detects idle and redundant data within each voice circuit resulting in a 56 to 1 bandwidth savings. WAN bandwidth is not consumed by silence or redundant samples.

T1 Over Wireless Ethernet

Interconnection of T1 based data communication systems over wireless as a primary or back up connection is a major application of the IPTube.

For over eight years the IPTube has proven itself around the world as an effective method for using Commercial Off the Shelf Wireless Ethernet Bridges to interconnect T1 circuits.

The IPTube's Assured Delivery Protocol has the sophistication required for solid performance across a wide range of wireless connections.

The use of parallel Wireless Ethernet links minimizes the latency and Radio’s packet processing requirement. 
Note: Parallel Application requires Ethernet Switch Option.

T1 Over Wireless Ethernet Diagram

Connecting phone systems across a wireless Ethernet connection has a return on investment that is measured in weeks. Eliminating the wired connection for the T1 based communication equipment is made possible with the IPTube's T1 Over Ethernet capability.

Cellular Base Station Backhaul

The IPTube G4 T1s provide transparent interconnection of Base Stations, Base Station Controllers and Mobile Switching Centers over IP Ethernet packet-switched networks.

Cellular service providers save substantially by converting to a packet switch network. The Lossless Data compression option, which is especially well suited to Cellular communication links, minimizes the bandwidth required to interconnect.

Cellular phone service providers are able to save substantially by converting to a packet switch network from circuit based TDM leased lines. The Loss Less Data compression option provides a 56 to 1 compression, which minimizes the bandwidth required to interconnect, is especially well suited to Cellular communication links. 

Engage's first deployment of the IPTubeT1, in the Spring of 2000, was for an international interconnection of a Cellular Base Station to a Base Station Controller.

The SuperTube Option reduces the overhead and packet frequency while lowering latency which makes cell backhaul a possibility over Wired and Wireless connections.

Note: The Ethernet Switch Option has the sophistication to support Ethernet Native Base Station applications with QOS and rate limiting.

Cellular Base Station Back Haul Diagram

Broadband Service Providers

Companies, that are able to provide IP Ethernet access networks generate new revenue by offering traditional T1 leased line and private line services, such as:

Cable Operators

Cable operators connect traditional T1 leased line and private line services over their hybrid fiber coax (HFC) cable networks. HFC Cable network latency typically requires echo cancellation.

Metropolitan Area Networks

Metropolitan carriers with IP or Ethernet access networks deliver traditional leased line and private line services.


Utilities generate new revenue by offering traditional T1 leased line and private line services over their fiber or power line networks.

Incumbent Carriers

Telcos reduce costs by delivering profitable leased and private line services over their flexible Ethernet infrastructures.

CLEC PBX Back Haul

The IPTube G4 T1 provides CLECs with a way to back haul T1 DS0s from a customer’s phone systems over their Internet connection. The back hauled DS0s are connected to the CLECs phone switch for connection to the Public Switched Telephone Networks. Local Exchange Carriers are able to offer an economical alternative to the local Phone Company.

International Toll Bypass

The IPTube T1's most dramatic cost savings is when it is used for the international interconnections of TDM based telecommunication equipment. The IPTube E1 is interoperable with the European TDM standard E1.


LAN Network Interface
  • One 10/100BaseT Full/Half Ethernet (2nd LAN requires Switch)
  • Auto Negotiation or Configurable Speed and Duplex
LAN Network Protocols Supported
  • Assured Delivery Protocol 
  • DHCP
  • DNS Address Discovery
  • Dynamic DNS
1 to 4 Duplicate Packet Transmission
  • Resilient performance through a lossy interconnect
T1/Fractional T1 Specifications
  • One to Four Port Models
  • Connects directly to T1 or DS1
  • Framing - ESF or D4
  • Coding - B8ZS or AMI
  • Supports DS0 assignments from 1 to 24
  • Non Contiguous Configuration x-y,z Supported
  • Comprehensive clocking:
    • Internal – the master clock source for the TDM circuit is provided by 
      an internal clock oscillator
    • Network/Loopback – the transmit clock is derived from the T1 port
      receive clock
    • Adaptive – the clock is recovered from the Ethernet network interface
      External - Stratum1 GPS Clock Synchronization
      OCXO - Stratum 3E
T1 Over IP Protocol
  • Assured Delivery Protocol
  • TDM Over IP
  • Circuit Extension Services Over IP - CESOIP
  • Frames Per Packet Configurable 8 to 56
  • Extremely low processing delay under 2 milliseconds
  • Low Latency Mode: 500 microseconds 4 T1 frames
  • Max Payload Mode: 7 millisecond 56 T1 frames
  • Configured jitter buffer to compensate for packet delay variance from 1.5 to 595 milliseconds
Lossless Data Compression Option
  • Detects idle and redundant data within each DS0
  • Configurable Silence Detection Range
  • Interconnect bandwidth is not consumed by silent or redundant data
  • Low Latency 8 to 1 Compression settings from 8 to 1 to 56 to 1
TFTP Online Upgrade Capable (FLASH ROMs)
  • IPTube is fully operational during upgrade
Quality of Service Support
  • IP Type of Service (TOS) CLI configurable
  • IANA Registered UDP Port 3175
  • Diffserv configuration of TDM Over IP header
  • VLAN tagging and priority labeling according to 802.1p&Q
  • T1 Over IP frames are tagged with a dedicated VLAN ID
Ethernet Switch Option
  • Out of band management interface with independent IP configuration
  • 802.1Q VLAN support with Filtering for up to 64 VLANs 
  • Support both port-based membership or 802.1Q VLAN-based VLANs
  • 2,048 MAC address entries with automatic learning and aging
  • CE
  • Safety -IEC60950
  • EMC - CFR 47 Part 15 Sub Part B: 2002, EN55022: 1994 + A1 & A2, EN55024, ICES-003 1997, CISPR 22 Level A 
  • Telecom Part 68
  • Remote config., monitoring, & reset
  • Secure Socket Shell - SSH Diffie-Hellman Group1/14 key exchange and strong integrity checking via MAC SHA1/SHA1-96 with Cipher AES-128 and 3DES and DSS and OpenSSH public key format
  • Telnet support with Edit and Paste Template Files
  • Console Port for Out of Band Management
  • SNMP support (MIB I, MIB II, Engage proprietary) with configured traps
  • Temperature: 0–50°C (32–122°F).
  • Optional Extended Temp ranges avail. 
  • Humidity: Up to 90% non-condensing
Rear Panel/Power
  • 10-30 VDC, 1.0A.
  • Screw Locking Connector
  • Power 7 Watts 
  • Universal Adapter 100/240 VAC 50/60 Hz
    Optional -48V 0.25 Amp
  • Hot Standby
Dimensions & Weight
  • Dimensions: Length 7” (17.78 cm); Width 5.5” (14 cm); Height 1.50” (3.81 cm) 
  • Weight: 2 Pounds (1 Kilogram)
  • Telco Diagnostics: Local Loop, Remote Loop, Loop Up/Down NIU and CSU Codes. Enables isolation of connectivity faults to local, network or remote equipment
  • Physical layer alarms for LOS, AIS, LOF 
  • Comprehensive statistics: LAN and IP layer network statistics: such as packet loss and packets arriving late, out of sequence, underruns, overruns CRC, and delay variation (jitter)
GPSDO Option
  • Receiver Input: 10MHzL1 C/A Code. Coarse Acquisition
  • Position Accuracy: typical 10 m RMS Tracking 4 satellites
  • Tracking: 12 parallel channels. Multi satellite ensembling with TRAIM
  • Acquisition Time: Cold Start <45 sec / Hot Start < 2 sec Re-acquisition < 1 sec 
  • 1PPS output accuracy:UTC(USNO):+/- 30 nS RMS 100ns peak
  • Frequency output accuracy: 1 X 10-12@ 1 day
  • Frequency/timing - Modified Allen Deciation frequency stability (TCXO):
    • 1 X 10-9 @ 0.1 sec
    • .9 X 10-9 @ 1 sec
    • .5 X 10-10 @ 10 sec
    • .9 X 10-10 @ 100 sec
  • Meets ITU–T G.811 Wander Generation Mask
  • Meets ETSI–PRC Wander Generation Mask (with OCXO reference)

Ordering Information

Part No.



IPTube G4 T1, xT1 *Note: x = Specified # of T1 Ports (1 to 4)


IPTube G4 T1, xT1 with xT1 compression, *Note: x = Specified # of T1 Ports (1 to 4)

Optional Features

Optional Features


GPS Disciplined Oscillator Module, Stratum 1 Clock Source


5 Port 10/100 Ethernet Switch with QOS / VLAN / Rate Limiter, Reserve T1 Over IP Bandwidth w Rate Limiter


SuperTube Option, Extends 4 T1 Circuits within 1 IP Packet Stream


ROHS compliant materials and processes, Restriction of Hazardous Substances no Pb


Protector Option, Fault Tolerant Network Interconnect. The protector option utilizes the second LAN interface as a redundant path for the interconnection of the IP encapsulated data. The extension of the IP-Tube has a fault tolerant link that is configured to always on, or with switch over criteria.  Learn more.


Alternator Load Balancing Option, Enable Alternator Load Balancing

Power Supply Options

Power Supply Options


Power Module 10/30 VDC ADAPTER, Ships with Universal Adapter 100/240 50/60


Power Supply Module Negative 48 Volt DC, Isolated Negative 48 Volt Power

Rack Mount Options

Rack Mount Option


3 Unit 19" x 1RU Rack Mount Kit for 5.5" Products

So What's Next?


Engage Communication
9565 Soquel Drive. Aptos, CA 95003
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Telephone: 1-831-688-1021
Toll Free : 1-877-ENGAGE4
Designed, Fabricated, and Assembled
in America 
Supported Worldwide