Advancements in push-to-talk-over-cellular (PoC) services have evolved to a point where they represent a threat to private land-mobile-radio (LMR) networks, potentially resulting in the construction of new LMR networks dwindling noticeably during the next five years, two speakers said during a recent webinar about PoC offerings.

“We’re talking about an enhanced push-to-talk system that is not mama’s push-to-talk system that Nextel had,” Steve Graves, chief information officer (CIO) for the city of Richardson, Texas, said during the webinar sponsored by AT&T (click here to access the archived session for free). “This is a push-to-talk system that actually connects to a trunked radio system. We’re doing it in Richardson.

“We tried Nextel back in the day, and we tried Verizon, AT&T and different push-to-talk services. The Nextel everyone liked, because it was a direct connect. The other services, at one time, were just dialing. It was a push to talk, but it was calling to the next phone—there was a hesitation, and it always messed people up. So that didn’t work out too well, either. The test that we’ve done here through our radio system has been direct connect and no hesitation. It feels more like a radio than it does an old-style push to talk.”

In fact, the city of Richardson has transitioned all non-public-safety employees from its private P25 network to the PoC system, but interoperability between the P25 and PoC networks is maintained via an ISSI gateway, Graves said. Public-safety personnel continue to use the P25 network as their primary method of voice communication, but they leverage the PoC system to talk with colleagues when out of P25 network’s coverage area, he said.

“We set up an ISSI connection with AT&T that’s encrypted,” Graves said. “The ISSI connection that we set up took us 15 to 30 minutes to get it operational. It takes me a week to put in a router for a network; it took me 15 to 30 minutes to put in an ISSI connection, where I was talking to public safety, where I was talking to parks, where I was talking to the different groups—we have an interface to their system that allows us to add and remove customers.

“I’m not saying today that everyone should run out and get this technology and hand it off to public safety and to the firemen, because it’s not going to work [as a standalone system for first responders]. What I’m telling you is that this is an enhancement today to what we do.”

David Krebs of VDC Research said the PoC market in the U.S. serves more than 3 million users today and is expected to more than double by 2019—projections that do not include potential PoC users that may leverage the much-anticipated FirstNet network that is expected to be deployed beginning next year.

While existing LMR network likely will continue to be used and maintained for more than a decade, the availability of PoC as an alternative means to access push-to-talk communications could be a noticeable decline in the need for new LMR systems to built, Krebs said.

“Five years from now, I have a hard time believing that significant new investment in LMR networks will be happening,” Krebs said during the webinar.