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T1 Failover (T1 Automatic Protection) Switch
T1 Protection (Failover ) Switch - 4 T1 Links (12 T1 Ports)

Product Overview

AceCom's T1 Fail-Over (T1 Protection) Switch (12 T1 Ports - 4 Links) allows the user to connect a single T1 line from the telephone company to an "active", as well as to a "standby" T1 terminal, such as data server / router etc. at the customer premises.

How it works?

In the event of the failure of the data server / router connected to the "A / active" port of the T1 Protection (Fail-Over) Switch, it shall automatically switch and connect the T1 line from the telephone company to the data server / router on the "B / standby" port. This ensures minimum downtime - which would have otherwise occurred due to equipment failure connected to the "A / active" port. This equipment may be used to enhance the reliability and the efficiency of the customer's data network.


  • Allows the user to connect a T1 line from the Telephone Company and to switch it automatically between an "active" and a "standby" T1 terminal at the customer premises. The user programmable switching criterion may be Loss Of T1 Signal, AIS and Loss Of T1 Frame.

  • Can accommodate upto four T1 lines - may be used switch between "active" and "standby" T1 terminals connected to upto four (or fewer) T1 lines.

  • Independent switching for each of the four T1 lines.

  • User programmable switching criterion - independent for each T1 line.

  • Built-in real-time clock / real-time logging maintains a history of all events.

  • Remotely accessible over a TCP-IP networks. Allows the user to access and carry out maintenance, or / and switch the T1 line(s) between the "active" and "standby" T1 terminals, remotely, if required.


  • Allows the users to install and maintain active/standby/duplicate customer premises data networks/data servers, without bearing the recurring $$ expense of leasing additional expensive T1 lines from the telephone company.

  • Automatically switches the T1 line from the Telephone Company between the "active" and "standby" T1 equipment at the customer premises, according to the customer-programmed criterion.

  • Improves equipment and data security.

  • Allows the user to co-locate the "backup / standby" equipment in a different room/building and prevent any data loss arising out of conditions of natural calamity such as fire, flooding etc.

  • Increases the reliability of the customer's data/IT networks without having to bear the recurring and additional cost of leasing additional T1 lines from the telephone company. The equipment may be used to create secondary/backup systems at the customer premises to provide virtually uninterrupted service.

Application Note

  • The T1 Fail-Over Switch should be used when the customer is using a T1 line to connect to and install "active" T1 equipment and "standby" T1 equipment (such as a ROUTER or a PBX) at the customers premises.

  • The T1 Failover Switch shall automatically switch the T1 line from the telephone company between the ACTIVE T1 data server / router and the STANDBY T1 data server / router. Should the ACTIVE T1 data server / router fail or be removed from service, the T1 line from the telephone company automatically switches to the STANDBY T1 data server / router without requiring any customer or user intervention.

  • 8/16 E1/T1 Links (24/48 E1/T1 Ports), 1+1 Automatic Protection Switching Equipment: This equipment is to be used when the customer wants to use two different E1/T1 links of the network to establish a 1+1 redundant path to ensure continued E1/T1 service between two points even if one of the network E1/T1 link fails. Example - the customer may want to use E1/T1 Optical Fiber and an E1/T1 Radio link and to provide an ACTIVE and a STANDBY link between a BSC and a BTS so that when the E1/T1 Optical Fiber (ACTIVE) link goes down the STANBY / REDUNDANT E1/T1 Radio link automatically  gets connected to provide continued connectivity and service between the BSC and the BTS.





User programmable criterion for switching between Active and Standby T1 Links at the customers premises:

Loss Of T1 Signal (LOS)

The Loss of Signal condition in a T1 may occur due to:

  • The failure of the T1 Port of the customer premises equipment.

  • Or due to loss of power to the customer premises equipment.

  • Or due to the disconnection of the T1 cable between the protection Switch and the T1 Port of the customer premises equipment.

The cause of LOF is 2 out of 5 Ft bits are in error for D4 Framing and 2 out of 5 frame bits are in error for ESF framing.

Loss Of Frame (LOF)

This Alarm is also known as Blue Alarm. This Alarm indicates unframed all ones being detected in the incoming pulses on the receiver of T1 Protection Switch.

Alarm Indication Signal (AIS)

This Alarm is also known as Yellow Alarm. This Alarm indicates in D4 Framed bit 2 of each DS0 for 255 consecutive channels has been detected as a zero.

Remote Alarm (RA)

When ESF Framed: Alternating eight ones/eight zeros have been detected in the ESF Datalink. A Yellow Alarm is typically transmitted to indicate a failure on the receive side of the Failed end.


This parameter is the number of CRC-6 errors (Cyclic Redundancy Check Errors) that occurred during the test period.

CRC-6 errors are only counted while the Telco T1 framing is selected as ESF (Extended Superframe). The CRC-6 can be monitored either on In-Service or Out-of-Service T1 Spans. Since the expected value of the CRC pattern can be anticipated, the received data can be compared to the expected results. Whenever the expected value does not equal the actual value a CRC error event is counted.

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Technical specifications are subject to change without notice.
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