December 2, 2025 by Joe Ross
There is a growing trend that public safety communications professionals need to keep an eye on: the use of a cellular backup on P25 devices. Some are using it to address holes in their systems, some for backup to their LMR networks. At the same time, the carriers are deploying Mission Critical Push To Talk or MCPTT along with advances in Low Earth Orbit (LEO) direct to device cellular communications (also known as Non-Terrestrial Network or NTN). Many use that term MCPTT, but there’s a cellular (3GPP) standard for MCPTT that everyone needs to be aware of. If we’re talking about 3GPTT MCPTT, that communication gets the highest possible priority on the cellular network, while “over the top” push-to-talk services will get priority over the general public’s data, but not other public safety uses on networks like FirstNet (or Verizon’s network slicing approach). Land mobile radio subscriber devices are now coming with cellular backups, but in the case of major widespread outages (think hurricanes or other events that affect wide areas and may bring down LMR towers too) everyone is going to be operating over the fallback LEO satellite operations in a region. And, given the limited capacity of LEO operations, it’s going to be critical that MCPTT is prioritized over all other public safety and public communications needs. So, if public safety wants to use this backstop for communications during these extraordinary events, it will be important that the dual mode (P25/5G) radios support the 3GPP specs for MCPTT and the NTN specifications. The current dual mode P25/cell radios don’t do that. No devices support the NTN specs, but the current crop of radios use “over the top” voice streaming over cellular. Given the extended lifecycles of public safety radios, the public safety community might want to start pushing vendors towards this support.