Case Studies:

Public Safety Network Chooses Telco T1 Lines To Replace 4-wire Analog Leased Lines


  • The leased lines provider was set to discontinue FDDA 4-wire analog lines
  • Cross talks and unwanted signals caused by aging lines
  • Needed to integrate JPS voters and Motorola receivers
  • T1 and Ethernet options were considered


A town in New England needed to upgrade their emergency communications system. Police and fire departments monitor over 8500 people throughout 24 square miles. Within the town there is a busy Interstate which carries extremely heavy volumes of cars and trucks daily to cities in New England and towards Boston, New York, and Maine. Keeping first responders and emergency personnel informed was a top priority.

Critical communications faced disruptions when the town's leased lines provider was set to discontinue FDDA 4-wire analog lines. Alternatively the provider offered T1 or Ethernet services to keep emergency services in operation. The town began their search for an economical solution to carry their network for years to come.


New network choices included T1 or Ethernet services. The town faced disruptions in service if they were unable to find a replacement for their FDDA 4-wire analog lines. Aged and faded analog lines were also present throughout the network. These lines caused unwanted signals and cross talks.

Upon identifying the main issues a trial network was set up with TC Communications. TC offered products for 4-wire Analog conversion: the TC8614 for T1 lines and TC3846-6 for Ethernet.


After consideration the town decided to choose T1 lines. Choosing T1 allowed for a more economical and expedient installation. A TC8614 with 600ohm Analog over T1 was the first product sent for testing. The equipment was able to leverage 4 channels with one unit; just like the FDDA analog lines installed before.

Cross talk was also an issue for the FDDA system. Once TC products were installed voice communications stabilized and disruptions within the network were eliminated. Dry contact is also supported.


It is often that public safety networks need their new purchase to work with previously installed equipment. The town had both JPS voters and Motorola receivers they were not prepared to retire. TC equipment was able to integrate with what had been put in place years before. Without that ability the town could have faced more costly upgrades and potential downtime as they sought a solution.


Since choosing a new system, the town has been able to keep their network running error free. They also experienced an upgrade in audio quality thanks to TC Communications equipment. During a heavy rain storm one weekend, most of the 4-wire circuits experienced interference and cross talks. It was thought that the newly installed devices may have caused the issue. Upon closer inspection the circuits connected to the TC Communications boxes received no disruptions.

The town was also able to ensure a longer life for their equipment at a lower cost than Ethernet with no downtime. New operating costs were comparable to their previous charges for 4-wire leased lines. Without improvements to their network, emergency services would have faced disruptions within their network. Now, with newly installed equipment and minimal change to the network, they can focus on surveiling the town.

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