IP-Tube GT1
BlackTube T1

Encrypted T1 Over IP

Secure T1 Circuit Extension
for Voice, Video, and Data

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9" (L) x 7.3” (W) x 1.50” (H)
Rack Mount and Power Options
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Rack Mount and Power Supply Options

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Rear Panel: 12/30 VDC Adapter (option)

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Rear Panel: 12/30 VDC Screw Term Adapter (option)

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Rear Panel: 12/30 VDC with Negative 48 VDC Screw Term Adapter (option)

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BlackTube T1

T1 Over Ethernet Encryptor

BlackTube T1

Encrypted T1 Over IP

- Secure T1 Circuit Extension for Voice, Video, and Data -

Product Image


9" (L) x 7.3” (W) x 1.50” (H)


AES Encrypted T1 Voice and Data over IP

The BlackTube T1 provides organizations with the ability to securely interconnect PBXs, Cellular Base Stations, Telecom Switches and T1 based communication 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 via LANs, WANs, MANs, Satellite and Wireless Ethernet.

The BlackTube T1 encapsulates full and fractional T1 circuits, along with their framing and signaling bits, into AES encrypted IP packets. Encryption of the packetized T1 protects vital information from eavesdropping, tampering and regulatory compliance violations. 

BlackTube T1s secure the Critical Infrastructure utilized by highly competitive businesses, government operations, banking and finance, telecommunications, emergency services, gas and oil, electric and energy, water, and transportation.

The BlackTube T1 ships with two T1 interfaces with either 1, 2 or 3 active and two 10/100 BaseT Ethernet Interfaces. The T1 interfaces have configurations that for provide independent protocol, compression, packet sizing, buffering, clocking, framing, coding and channel settings. The inactive T1 Ports can be activated via a software-based license key for a pay as you grow option.

Transparent Interconnect

The BlackTube T1's transparent operation maintains the proprietary signaling required to support PBX features such as call conferences, call forwarding, caller ID and SS7. Legacy phone equipment investment is preserved.

Signaling Support

PRI ISDN, SS7, and Proprietary out of band are supported. Transparent support for Data, Modem or Fax. Voice quality is not compromised.

E1 over IP Voice and Data Diagram

BlackTube 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 BlackTube T1 employs Engage’s robust Assured Delivery Protocol with the following benefits: 

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

Dual LAN Interfaces

All BlackTube T1 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 
  • The LAN ports can be configured to support connections over 2 opposite ADSL links 
  • Alternator Option for load balanced SDSL interconnects 
  • Protector Option for Redundant Packet Path connections with Constant or Switch Over Criteria

Service Quality Packet Prioritizing

The BlackTube T1 uses the Type of Service byte in the IP packets or 802.1p/q mac levels for prioritization of the encapsulated T1 frames. QOS is used to ensure that the real time Circuit data from the BlackTube T1 is ensured high priority.

Full T1 Connection Across Two ADSL Lines

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

Virtual Private Network Support

Interconnecting the BlackTube 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.

Virtual Private Network Support Diagram

BlackTube T1 Optional Features

DS0 Time Slot Multiplexer Option -MUX

The BlackTube T1-MUX maps DSOs from a central site to as many as 31 remote locations via an IP/Ethernet connection. Get maximum use of expensive DS1 interfaces on PBX, Channel equipment and datacom gear. Also provides Virtual DACS Over IP capability. Mesh DS0s one-to-many or many-to-many.

MUX Option Diagram

T1 Switch Option -SWT

The T1 switch option enables the T1 Port 1 interface to be manually switched between a T1 circuit connected to T1 Port 2 or to T1 Over IP packets connected with the remote Black•Tube T1.

  • Remote Control of T1 Connection to Telco or T1overIP
    Installation performed by a single Technician 
    Quick reversion to Telco during debug of T1overIP
T1 Switch Option Diagram

T1 Link Protector Option -LPT

The T1 Link Protector provides an automatic back up for T1 circuits with T1 Over IP connecting via Wireless Ethernet, Gigabit Ethernet, IP Satellite Services, xDSL,....

  • Automatic Protection Switch for T1 Circuit
  • Deliver on Stringent Service Level Agreements
  • Back Up for Mission Critical Connectivity
  • Disaster Recovery for Public Safety Network
LPT Diagram

Lossless Data Compression Option -C

The BlackTube T1-C 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.

Compression Diagram

Alternator Load Balancing Option -ALT

The BlackTube T1-C 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

ALT Option Diagram

Rate Limiter Option -RLM

The BlackTube T1-RLM 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. The data rate governor utilizes Time Division Multiplexing based clocking to provide for Nx64, NxT1 and NxFT3 bandwidth regulation that is configured from 64 kilobits up to 45Mbits.

RLM Option Diagram

Protector Option -PRO

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 -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 Black•Tube T1 also supports the transmission of multiple duplicate packets to support Mission Critical Circuit extension with redundancy that is only limited by the bandwidth provisioned. 

-EnPRO Option Diagram

Pay-As-You-Grow Field Upgrades

The BlackTube T1s are designed for Pay-As-You-Go growth from 1 T1 to 3 T1s. Customers can elect to economize initial installations, buy purchasing a single active T1 port and enable additional T1 Ports via a software-based license key.

Field Upgrade benefits are extended to our Industry-Best Loss less Data Compression. Just as T1 ports are field upgrade able, so is Loss less Data Compression. At any time, each T1 port on the BlackTube T1 can be upgraded to Loss less Data Compression with a simple software-based license key installation. If you determine that your BlackTube T1 is best deployed with Loss less Data Compression, you're still in business with the per port field upgrade!

Rack Mount Kit

The Black•Tube family is ready for your most demanding central office or data center environments. With the Rack Mount Kit, BlackTube T1 products are easily installed in 19" and 23" racks. Easy access to both front and rear sides facilitates technician maintenance procedures.


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 BlackTube T1 provides organizations with the ability to securely 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 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.


Wide Area Networks that have sufficient bandwidth and Quality of Service provisioning result in very significant cost savings especially for Multinational corporations. The BlackTube T1-C with lossless 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.

Wireless Ethernet

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 IP Tube’s T1 Over Ethernet capability.

UnEncrypted interconnection of PBX connections across Wireless is able to be eavesdropped with Shareware Packet Capture programs. The BlackTube T1 ensures that private branch connections across wireless networks remain private.

IP Cellular Back Haul Diagram

Cellular Base Station Backhaul

BlackTube T1's are used to provide transparent interconnection of the Base Stations, Base Station Controllers and Mobile Switching Centers over IP Ethernet packet-switched networks.

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 40 to 1 compression, which minimizes the bandwidth required to interconnect, is especially well suited to Cellular communication links. 

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

Cellular Base Station Backhaul 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.

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 BlackTube T1-Ecan provides CLEC's with a way to back haul T1 DSO's from a customer's phone systems over their Internet connection. The back hauled DSOs are connected to the CLEC's 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 BlackTube T1's most dramatic cost savings is when it is used for the international interconnections of TDM based telecommunication equipment. The BlackTube T1's are interoperable with the European TDM standard E1.


Encryption Algorithm
  • AES 256-bit
  • Fully Automatic key management 
LAN Network Interface
  • Two 10/100BaseT Full/Half Ethernet 
LAN Network Protocols Supported
  • IP, TCP, UDP, ICMP, Telnet, SSH
  • DHCP
  • DNS Address Discovery
  • Dynamic DNS E1 Over IP Protocol:
  • TDM Over IP
  • Circuit Extension Services Over IP 
  • HDLC Over IP
  • Assured Delivery Protocol 
WAN Network Protocols Supported
  • HDLC, SDLC, PPP, Frame Relay
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 
Echo Canceller
  • Voiceband Echo Cancelling according to ITU G.165 and G.168
  • u- and A-Law coding according to ITU G.711
  • 24 channels with end echo path delay of less than 63.75 ms
1 to 4 Duplicate Packet Transmission
  • Resilient performance through a lossy interconnect
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 
  • Compression settings from 8 to 1 to 40 to 1
  • 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 Part68 
  • Secure Socket Shell - SSH
  • Telnet support with Edit and Paste Template Files
  • Console Port for Out of Band Management
  • SNMP Public and Private MIB support with configured traps
TFTP Online Upgrade Capable (FLASH ROMs)
  • BlackTube is fully operational during upgrade
  • 9" (L) x 7.3 ” (W) x 1.50” (H)
  • 0° to 132° F (-10° to 50°C ) operating temperature
  • Up to 90% operating humidity (non-condensing)
  • Optional Extended Temperature Range available
  • 10-30 VDC, 1.0A.
  • Screw Locking Connector 
  • Universal Adapter 100/240 VAC 50/60 Hz
  • Optional -48V 0.25 Amp
  • Hot Standby
Quality of Service Support
  • IP Type of Service (TOS) CLI configurable
  • IANA Registered UDP Port 3175
  • 802.1p/q mac level prioritization

Ordering Information

Chassis Slot Card: BlackTube T1 Over Ethernet Encryptor

Rack Mount & Power Supply Options:

BlackGate RS232 Rear
BlackGate RS232 Rear

Part No.



Black•Tube T1, xT1, *Note: x = Specified # of T1 Ports (1 to 3)


Black•Tube T1 Port Upgrade, Enable Additional T1 Ports (up to 3)


BlackTube T1, w/ xT1 Lossless Data Compression, *Note: x = Specified # of T1 Ports (1 to 3)


BlackTube T1, Compression Upgrade, Enable Lossless Compression T1 (up to 3)

Optional Features

Optional Features


Echo Canceller Card 1 to 3 T1, Add Echo Cancellation Specify # of T1s


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


T1 Multiplexer and DACS, Groom 2 to 31 remote locations Over IP


Rate Limiter Option, Reserve T1 Over IP Bandwidth


T1 Switch Option, Provides for Manual Switching of T1 or T1 Over IP


Link Protector Option, Automatic T1 Circuit Backup with T1 Over IP


T1 Coaxial 75 OHM Option, Ports Impedance -120 Ohm Default


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 BlackTube 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


90-220 VAC Universal International/Domestic Adapter


DUAL REDUNDANT, 90-220 VAC Adapter


Internal Power Module, -48 VDC Screw Terminals


DUAL REDUNDANT, -48 VDC Screw Terminals


WIREDC Option, +24 VDC Screw Terminals



Rack Mount Options

Rack Mount Option


Rack Mount Kit - for single 7" products (Fits both 19" and 23" racks)


2 unit 19" x 1RU Rack Mount Kit for 7" products




Right Angle Wall Mount Bracket Kit

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