Speech Plus Data System

InterTalk’s™ Speech Plus Data System (SPD) is utilized to control your agency’s Speech Plus Data radio trunks and/or base stations over legacy analog lines. InterTalk’s SPD is housed on a Linux-run server platform, and each SPD Controller can be configured to control up to 192 polling radio trunks over eight T1 spans. InterTalk's SPD System can also be configured for complete redundancy, ensuring no critical communications or information are lost to outages or unforeseen circumstances.

Learn more about InterTalk's complete Rail communications ecosystem.

Read our White Paper entitled "Modern Speech Plus Data Systems".

console radio


Trunk Controller

  • Accepts socket connections from the ILS Server
  • Can simultaneously handle up to 192 radio trunks
  • Option to separate data from voice (data sent via IP socket, voice via T1).

SIP/VoIP Interface

  • Routes radio trunk audio between InterTalk Logistics Supervisor and DSP SPD Modem
  • Includes TX VOX detection to support VOX PTT when enabled.

Maintenance Interface

  • Web-based management of maintenance and configuration of the SPD Controller Server
  • Database management for storage and retrieval of configuration/diagnostic data
  • Real-time diagnostic support and archived usage statistics.


  • Manages SPD Modem encode/decode functionality
  • Separates voice and data on received audio from the radio trunk T1 Interface
  • Combines voice and data in transmitted audio to the radio trunk T1 Interface
  • Handles DTMF and 2-tone paging encoding.

T1 Interface

  • Embedded Asterisk server interfaces audio and data streams to T1 Cards DS0’s
  • Handles SIP registration alarm reporting to the InterTalk Logistics Supervisor Server.
Key Features: 
Built-In Maintenance Tools
Loopback of switch and trunk side audio
Test tone generation toward trunk or switch
Audio to and from the radio trunk DS0 can be monitored from a technician’s maintenance console
Route any trunk polling data to an NLS port or IP socket; time-stamped data indicates TX or RX
Tracked polling statistics include missed polls, Base fails/ recoveries, poll response time
Message Log includes startup/shutdown/failover events, trunk controller events, and more
Error Log includes any alarm or errors encountered during operation
Product Specs: 

Processor: Intel Core i3 or better

Ethernet Connections: 3x Auto-Sensing 10/100/1000 Mbps ports

Serial Connections: 2x USB 3.0 ports for high-speed peripherals

Operating System: Linux

AC Input Power Requirements: 100/240 VAC, 50/60 Hz, 40 Watts

Standard Warranty: One (1) Year

Dimensions: 3.38" x 17.54" x 27.25" (8.59 x 44.55 x 69.22 cm)

Form Factor: 1U, standard 19” rack mounting

Weight: 8.8 lbs (4.0 kg)