Tait Talks: P25 Standards Continue to Address User Needs

Sandra Wendelken joined Tait in July 2023 after working for three years at market research firm IDC as senior research analyst covering mobile and IoT services. For 15 years, she was editor of ‘MissionCritical Communications’ and ‘RadioResource International’ magazines covering the public safety, critical communications and LMR industry. Today we get a deep dive into her insights at her new role at Tait!

In my new role as market insights manager at Tait, I attended APCO 2023 in Nashville in early August. I had not been to APCO since 2019 because of a three-year hiatus from the two-way radio industry to work in market research analyzing wireless topics such as business and consumer wireless services, IoT cellular connectivity, and private 4G/5G networks. So APCO was the perfect place to catch up on the latest technology and innovations in the U.S. public safety communications market. I must say it is great to be back!

Sandra Wendelken – Tait Communication’s Market Insights Manager

Because of Project 25 (P25) technology’s importance in the U.S. market, I was keen to learn what I had missed during the past few years. During the sessions focused on P25 standards updates, which were well attended by P25 practitioners, security was a strong theme with several new security enhancements being worked through in the standards process. The TIA Engineering Committee TR-8 differentiates three types of P25 security: user authentication, Advanced Encryption Standard (AES) 256, and Link layer Encryption (LLE). Standards leaders would like to see all public safety agencies discontinue use of nonstandardized encryption (DES), however, they also recognize this is difficult without funding to upgrade and reprogram equipment to AES.

Recently, security vulnerabilities were discovered within the TETRA standard, an LMR technology heavily used in Europe and other parts of the globe. A similar third-party group pointed out P25 security concerns several years ago, and the TR-8 committee has further prioritized security since then. Considering the high number of cybersecurity breaches we read about in the news and the many more that are never publicized, a heightened focus on security is a pragmatic approach.

Following is a list of updated or new TIA TR-8 standards around the P25 standards:

  • New recommendations for mobile/portable receiver interference rejection because of interference from band 14 and band 17 cellular networks
  • Improving noise for coverage 
  • New emergency alarm indication for trunking/conventional
  • New user alias download features for trunking
  • New location on PTT feature for trunking 
  • New NIST-approved over the air rekeying (OTAR) message authentication method
  • New P25 link layer (air interface) encryption service protecting all air interface signaling
  • Control of “group regrouping” across ISSI and CSSI
  • New interoperability and conformance tests for ISSI and CSSI
  • Modifications to ISSI, CSSI, and DFSI to enable future interworking with broadband cellular public-safety systems

As a participant in the P25 standards process and manufacturer of a full portfolio of infrastructure and subscriber devices, Tait is a leader in P25 technology. The Tait TP9800 P25 multiband portable radio, its interoperability benefits and many features generated much buzz among APCO attendees. And Tait’s TP9600 and TP9400 series radios also fulfill user needs in the market with features specific to various models including color screens, intrinsically safe certifications, and man down capability. The Tait Tough durability feature extends across the full product line.

While P25 is a workhorse technology in the public safety sector for mission-critical voice communications, first responders also have broadband communications requirements. There was much discussion at APCO about the benefits of P25 and LTE commercial networks working together to provide both voice and data communications to mission-critical users. The Tait Axiom portfolio combines the two technologies within several form factors, including a mobile radio and wearable device.

The P25 standards work on the Inter RF Subsystem Interface (ISSI), Console Subsystem Interface (CSSI), and Digital Fixed Station Interface (DFSI) have set the stage for advanced interoperability. Separate P25 networks often need to interoperate, and the P25 ISSI can help overcome this challenge. The CSSI and DSFI enable P25 radio networks to connect to dispatch consoles to ensure seamless connections and improved communications. The standards work around these technologies continues, along with helping them interwork with broadband commercial networks. Tait is a champion of open standards with products incorporating all three interfaces.

I am impressed with the strides the industry has made in the past few years. Industry experts are ensuring mission-critical communications customers’ immediate needs are being met, while also looking to the future with innovation and vision that will further the mission of first responders. Tait is proud to be part of the process.

Stay tuned for more Tait Talks – Written by Sandra Wendelken


  1. Excellent!! Very much appreciate reading your article.
    It is great to have you back.

    Best Regards

    Take Care


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