The Importance of Mission Critical Push-to-Talk (MCPTT)

Mission Critical Push-to-Talk (MCPTT) is an international 3GPP standard that allows public safety agencies to use broadband cellular networks (4G/LTE and 5G) with the same one-button Push-to-Talk feature as their traditional Land Mobile Radios (LMR).

In plain English, MCPTT makes a smartphone as quick and easy to use as a one-button PTT LMR handset. What makes MCPTT so different is that it uses the high-speed data capacity of cellular networks to enable live video streaming, file sharing, and real-time location tracking, capabilities that traditional voice-only radio systems simply cannot match.

“Mission Critical Push-to-Talk is an absolute necessity for first responders,” said Michael Barnbeck, Deputy Executive Director of the Public Safety Broadband Technical Association (PSBTA) and Chair of the PSBTA Technology & Innovation Committee. “It is a necessity for first responders so they can go ahead and effectively keep the community safe and protect the lives of their community members.”

What Is Mission Critical Push-to-Talk (MCPTT)?

As mentioned above, MCPTT allows first responders to use their smartphones for instant, one-button voice communication, just like traditional two-way radios.

However, MCPTT is more than just a “walkie-talkie app”. Because it is built on strict international standards (3GPP), MCPTT is integrated directly into the cellular network’s core. As a result, data, video, and voice calls go through in milliseconds, matching the speed of traditional radios.

Another key difference: MCPTT over wireless broadband complies with rigorous performance requirements (Quality of Service) that consumer apps do not meet.

“In general, MCPTT offers higher grade standard features, functionality, encryption, reliability, robustness that does not exist with standard Push-to-Talk,” said Barnbeck. “LMR-based PTT can only handle voice and very limited data, whereas MCPTT handles voice, video, and large amounts of data. Since public safety consumes tons of data nowadays to effectively protect our communities, MCPTT is the logical choice for first responders.”

Features that Define MCPTT

Besides the items outlined above, there are certain key 3GPP-defined features that make MCPTT stand out.

Priority & preemption for first responders

MCPTT users enjoy “priority and preemption” service on FirstNet’s broadband cellular network. “This means that, when a network is congested with traffic during emergencies or major public events, first responder traffic goes ahead of all non-first responder traffic,” Barnbeck said. “Preemption means that if the network is full, non-first responder traffic may be disconnected temporarily to allow first responder traffic to go through. Say it’s New Year’s Eve at midnight: If the network is bogged down, first responders have first right of access to get their messages out first.”

Low latency

Latency is the amount of time it takes a signal to move from one end to another. In standard PTT, the time between when someone sends a voice message and when they get an answer can be measured in seconds. In MCPTT transmissions, this delay is cut down to milliseconds, which is why MCPTT is described as having low latency.

“In public safety, milliseconds matter,” said Barnbeck. “When lives are on the line, you have no time for delays. This is why low latency matters.”

Interoperability

Interoperability refers to the ability of different communication systems to talk to each other without problems. This ability is paramount for first responders, especially when multiple police, fire, and EMS agencies are responding to the same incident scene.

MCPTT offers two kinds of interoperability. The first is LMR-to-LTE interoperability, where an electronic gateway allows mobile radios to connect to smartphones, and vice versa. The second kind is cross-agency interoperability, which allows first responders from different departments to talk to each other no matter what equipment they’re using.

“This level of interoperability absolutely does not exist on standard PTT,” said Barnbeck.

How FirstNet Supports Mission Critical Push-to-Talk

As the only nationwide broadband wireless network in the U.S. specifically designated by Congress to prioritize first responders, FirstNet not only supports MCPTT, but takes it to the next level. That’s because only FirstNet has access to Band 14, the Congressionally-authorized section of the 700 MHz spectrum prioritized for first responders. FirstNet is also the only U.S. broadband wireless service to provide Priority and Preemption service to first responders across its entire product portfolio, not just MCPTT.

There are three FirstNet MCPTT products to choose from.

FirstNet Push-to-Talk is FirstNet’s standard MCPTT app that turns a smartphone or rugged device into a mission-critical radio.

FirstNet Rapid Response is a version of MCPTT for agencies who want to upgrade easily from AT&T’s commercial “Enhanced Push-to-Talk” service.

FirstNet Fusion is a MCPTT package designed to interconnect between LMRs and smartphones. It allows FirstNet member agencies to integrate their legacy land mobile radios with smartphones, for the ultimate in interoperable connectivity.

What’s Next for MCPTT

The next stage in the 3GPP evolution of MCPTT is MCX, aka “Mission Critical Services.”

In addition to existing MCPTT, MCX includes MCVideo (allowing the user to stream live video with the push of a button) and MCData (sending graphics, photos, and other data over the same MCPTT channel).

All of this expanded capability will require much more bandwidth. “This is why FirstNet is investing $6.3 billion to upgrade its wireless broadband services to include 5G,” Barnbeck said. “All of this money is coming from subscriber fees, not taxes. It will ensure that FirstNet will offer first responders the most reliable, robust, and functional MCX services as they become available.”

Together, these capabilities will move first responder communications from voice-centric coordination to real-time situational command.

FAQ

What is Mission Critical Push-to-Talk (MCPTT)?

MCPTT is an international standard that allows public safety agencies to use their smartphones with the same one-button Push-to-Talk feature as Land Mobile Radios.

How does MCPTT differ from regular push-to-talk systems?

MCPTT can carry voice, video, and data calls, while consumer and legacy PTT can only carry voice. MCPTT has much lower latency than PTT and is more reliable.

Why is MCPTT important for public safety and emergency response teams?

MCPTT allows first responders to access a full range of broadband wireless apps with the push of a single button.