Four Tips for Agencies Considering Mission Critical Push-to-Talk Apps

A myriad of commercial push to talk application options exist for public safety users, and for good reason. There are many benefits that can be realized by interfacing an existing mission critical land mobile radio system with a commercial push to talk service. You can read all about these benefits on our earlier post, “What is commercial push to talk technology and why does it matter for your public safety land mobile radio strategy?”

Or you can download our free whitepaper on this topic, “The Case for Push to Talk Technology in Public Safety.”

In this post, we will summarize what’s available in commercial mission critical technology, provide some detail around how the solutions work and what their advantages and disadvantages are.

At a very basic level, there are essentially three classes of PTT apps that integrate with LMR systems.

• LMR-based – Apps that are available from traditional LMR vendors such as those that are provided by Motorola Solutions and Harris Corporation
• Carrier-integrated – Apps that are available from commercial wireless carriers
• Third-party – Apps that are available from third party providers

Push to talk apps available from traditional land mobile radio vendors

The apps available from industry-leading LMR vendors enable public safety agencies to extend LMR talkgroup traffic to user-provided smartphones operating on commercial data or Wi-Fi networks.

Both vendors have some differences around specific solution features, however, both applications are similar in how they allow a LMR radio system to pass along emergency identifications, PTT IDs and alias information, thus allowing users to access the same information and emergency features as primary system users.

Despite this advantage, these solutions are typically proprietary and sold to buyers of larger, high-priced P25 systems, making them harder for smaller agencies and/or smaller convention systems to digest without incurring high costs.

Push to talk apps available from commercial carriers or third-party providers

On the other hand, agencies can procure apps from either their commercial cellular carrier or other third-party vendors.

AT&T, Verizon and Sprint all offer their respective flavor of PTT applications that can be integrated with LMR systems using software developed by Kodiak.  These vendors offer their PTT service as an extension of their cellular service with some additional priority levels being integrated on the network for the PTT application. These providers charge for their service with a monthly fee added to your wireless bill.

Alternatively, many third-party providers offer PTT applications that are not affiliated with a specific vendor. These applications leverage any available data pipe, including any commercial network or WiFi. The provider then bills directly for PTT service. Some of the ones we’re familiar with include ESChat and Cisco.

Again, each solution offers its own unique service offering. Fundamentally each solution works the same—a PTT system that integrates with an agency’s LMR channel.

The advantages of these solutions are that they aren’t proprietary to a radio system vendor and they offer lower price points that are better suited for small systems. They have one major limitation—they are dependent on standardized radio system interfaces and may lack features that are available with LMR interfaces.

What you should keep in mind if you're considering a commercial PTT service for your mission critical LMR system

Step 1: Publish a RFP.

Consider publishing a request for proposal to solicit PTT service. (Read more about the best way to go about this process with this post. Still feeling uncertain? Learn more about our expertise in this arena.)

Step 2: Weigh the pros and cons.

If you’re making the investment, be certain to understand the interface being offered to you and what its pros and cons are.

Step 3: Secure an inter-rf subsystem interface.

If you’re planning on purchasing a P25 system soon, secure an inter-RF subsystem interface (ISSI) upfront to ensure better pricing and availability when you’re ready to implement a future commercial PTT solution.

Step 4: Include a long-term migration plan for PTT now.

Make sure the solution your adopting includes a long-term migration plan for mission critical PTT, the 3GPP standard currently under development that will provide a common interface for PTT applications.

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