PTT over Cellular: A brave new world
Written by: Sam Fenwick | Published:
PTT over Cellular is particularly suited to end-users requiring wide-area coverage, such as skip hire, road haulage, couriers and taxis; image credit (top left panel): Flickr/lee bristol

Push-to-talk over Cellular (PoC) solutions have been in the market for years but are
starting to come into their own thanks to 4G networks and new hardware designed for
PTT users, especially for those on the move. Sam Fenwick looks at the current state of play

Push-to-talk over Cellular (PoC) has been around for a while and Tim Allerton, the founder of Push To Talk International (PTTI), should know – he’s been in the business since 2007 and the company started its live service on a 2G service one year later. The open standard on which all true PoC services (as opposed to VoIP) depend, OMA PoC was designed to work “over very slim data networks”. However, it’s only now that it’s truly starting to take off, thanks to the huge and ongoing investment in the nation’s mobile networks.

“At 2G, it was okay, at 2.5G it got better, at 3G it became what we think is very commercially available and that’s where we had a significant up-turn in our world where we started to do work with the bus companies and 4G has lit the company up,” Allerton says. The other factor that has boosted interest in PoC is the fact there’s now a large selection of “walkie-talkie two-way radio Android devices, which are built as professional two-way radios. These have a PMR-esque speaker, a solid-good mechanical PTT button, very large batteries (up to 5,000mAhr) and the ability to be plugged into desktop chargers – they no longer use micro/mini USB chargers”.

Syndico has recently entered the PoC market as part of a collaboration with PTTI. Andy Wilson, Syndico’s managing director explains why. “We’ve lost business over the years to cellular technologies and we’ve lost taxi business to PDA and other database devices, so we thought there was a gap in the market that could be filled by our dealer channel colleagues.” He notes that Dolphin, Fleetcom and Band 3 wide-area solutions have all “came and went”. These used to be sold by Syndico’s dealers and generated a lot of ongoing revenue from subscriptions. “We thought we’d fill that gap with PoC – I had a relationship with the founder of Push to Talk International many years ago, and we just reconnected
and thought it would be a great idea to work together.”

Wilson says the relationship between the two companies is founded on more than friendship. “We talked to several different vendors, but the PTTI package just came out on top for all-round performance, the performance of the system, the price package and then the technical support and ongoing development that PTTI is putting into the product – those things made it for me.”

“At Syndico, we don’t see this as a replacement for PMR radio,” says Wilson, “we see it as a completely different solution and we think it’s going to open up new markets for our resellers and recover some old customers back to our channel.”

He gives businesses with users who need to travel a lot such as couriers, taxis, haulage and skip hire companies as ideal candidates for PoC technology, along with companies that have multiple sites spread out across large areas, such as a security firm patrolling multiple industrial estates or a retail firm with lots of outlets across the country that want them to stay connected.

Adam Lowery, director at iPTT, also emphasises PoC’s appeal to those on the move. “If you ask any two-way radio dealer how many times they’ve been asked for radios that will work over 50 miles, they’ll laugh at you and say ‘every other day’. Traditionally they didn’t really have an answer. They’d say ‘you’d have to use a repeater or hire a slot on one’, but that becomes really expensive and cumbersome...” He explains that with PoC, even small numbers of users can benefit from the features associated with modern high-end radio systems, without having to pay for expensive infrastructure and radio licences. Speaking of which, Hans Becker, iPTT’s director of distribution, highlights the difficulty in getting Ofcom licences within the confines of the M25, “because of the congested airwaves in the London area”, and he sees this as a specific area where he thinks PoC will take off. Becker also highlights the ability for PoC devices with SIMs sold in the UK to work in continental Europe thanks to the EU’s Roam Like at Home initiative.

Syndico’s Wilson says that it and PTTI are developing a system to integrate PoC with DMR systems, in a similar manner to Tait’s UnifyVoice and Motorola Solutions’ Wave, and that it will work as long as the DMR system is Tier II or Tier III. Similarly, iPTT can use “an integration solution to combine analogue, radio, any other type of radio” with its PoC service.

PoC systems, like some DMR Tier III systems, offer over-the-air programming – enabling dealers or their customers to manage handsets remotely and eliminating the need to regularly travel long distances to perform simple tasks. Lowery says this feature is particularly useful for Shopwatch schemes as they rely on call ID when using DMR systems, so they can know which shop is speaking during emergencies.

“We’ve already implemented PoC into Shopwatch schemes and they think it’s fantastic because they don’t have to spend all the money on infrastructure. The device that sits in the shop is probably used once or twice a day, but they know there’s not going to be a problem, they’re not going to have to call the control to then relay a message onto another part of the town – it can all be done instantly”

The resilience question
For Jamie Bishop, Tait’s marketing manager for the Europe, Middle East and Africa region, PoC is more about opening-up existing DMR networks to more users through its UnifyVoice system than using it on a stand-alone basis. “Tait is embracing PoC technologies, but it is very early days for major users to drop their radios entirely and move to a PoC option. Most users looking to PoC are those who haven’t previously used a PTT solution, or those looking to augment their PMR system with the value unlocked by being able to use a smartphone interface.”

Bishop says “it would be very difficult for an existing PMR user to confidently move fully to PoC,” highlighting the way in which the Emergency Services Network (ESN), which is being developed for UK public safety users, is a unique case as “there is an agreement with the network operator that there is quality of service (QoS) and the customer – the Home office will be adding coverage where required.”

However, there are instances where PMR’s limitations are forcing organisations to take a good look at PoC as an alternative. iPTT’s Lowery says it is working with one of its dealers to replace a wide-area PMR system for a haulage company based in London that needed to expand it but couldn’t do so because the extra Ofcom licences weren’t available. “They’ve come to us through one of our dealers in the South. They’ve had our PoC system on trial and they’re looking at [installing PoC in] 250 vehicles… instead of the PMR system that they’ve been using.” iPPT can supply PoC mobile terminals that are “essentially plug and play” and come with internal antennas.

Airphone is a Belfast-based radio company. Lowery says that one of its customers, a council in Northern Ireland went down the PoC route, instead of spending “just short of £20,000” on the DMR infrastructure required to cover their entire area. “They tested it for months because they couldn’t believe it, they were really trying to make it fail and find a downside to it, but they couldn’t. They saved a fortune, they got a better system with GPS tracking, call-recording and call-logging – that’s all built in as standard on our system, it’s not an extra, it’s just part of PoC – how it works is all included. So, they got a much higher level of system for a tenth of the price.”

Another of iPTT’s indirect customers, a surveillance company in Manchester, is looking at PoC for both the coverage as “they want to cover most of the North West of England and have traditionally rented DMR capacity on hill-top sites”, and also for the encryption and privacy. “They know they’re not going to have any eavesdropping on their calls,” Lowery says, adding that there are devices on the market that can decrypt DMR conversations – “it’s not as secure as people make out”.

He explains that the mobile phone networks are already encrypted to a high standard and “our calls are then encrypted on our cloud system from device to device, so the chances [of eavesdropping] are slim to nil.”

To Bishop, the challenge with PoC “isn’t so much with the service/software, but the cellular networks on which you would need to rely for wide-area coverage. So in a controlled environment such as a company’s offices, airports or other complex, the service can be guaranteed using private Wi-Fi or a cellular DAS solution. To get an approximate wide-area coverage, it is possible to rely on PoC technologies, but to guarantee coverage whichever technology is used, some private wireless bearer is likely to be required”.

Part of the issue is that public cellular networks aren’t as hardened against long power cuts to the same extent as their mission-critical counterparts, such as Airwave (which is due to be phased out in favour of ESN). But they do have a greater number of locations served by overlapping cell sites (so service can still be provided if one site goes down). If you’re an end-user, consider whether the level of availability provided by cellular networks is compatible with your business model and if your other business processes (and those of your customers) are sufficiently robust for the extra resilience of a private PMR network with a UPS and back-up generator to make a difference in this kind of scenario – and if you can afford it.

Many PoC providers can offer devices with dual or roaming SIMs to reduce coverage issues or the impact of problems on a single network. iPTT also offers a Quality of Service SIM that constantly tests all the available cellular networks and uses the one with the best data transfer rate and latency, rather than simply picking the one with the best signal. Similarly, PTTI can offer SIMs with static IP addresses, which tend to provide a better quality of service than their dynamic cousins. Both these PoC services use servers located in the UK to ensure DMR-levels of latency – Lowery demonstrated this to me during a conference call – offer call recording, GPS tracking and provide dispatch software. “In our view, PTTI’s dispatcher does everything that a very sophisticated TETRA radio system does,” says Allerton.

Given that PoC systems can be quickly deployed with no need for additional infrastructure and can come reprogrammed and ready to work, there’s always the option of trying it out on a trial basis, especially as PoC firms are happy to lend them out to interested parties.

“What we find works best is putting equipment into hands, says iPTT’s Lowery. “We’re keen to lend our dealers equipment so that they can go out and put equipment into the hands of end-users. We find that when they actually get it and use it in real-life, it blows them away and they go ‘why haven’t we seen anything like this before?’.”

Moving towards a single device
Wilson firmly believes that PoC is a hardware-driven sale for dealers – “There’s no point having a slick system that provides fantastic functionality if the end-user isn’t thrilled and delighted by the hardware you put in his hand. Without the right hardware, you’re not going to make sales with PoC.” Syndico has opted for the traditional “good, better, best proposition”, in that it offers a basic device “which looks like an entry-level radio”, a mid-tier Android device and a high-tier Android smartphone, all of which are IP67 at a minimum.

Typically, PoC Android devices can be locked down so that they can either run just the PTT application or a selection of applications specified by the customer to prevent users from wasting time and data on social media and games. iPTT has side-stepped this issue entirely, offering PoC in a traditional two-way radio format, complete with channel selector and volume control knobs on the top of the handset.

PTTI’s Allerton believes one of the biggest wins as far as hardware is concerned is the way in which PTT-enabled smart devices allow customers to converge towards a single device for their staff. “An end customer cansave a great deal of cash by putting all his capability onto one smart device – that’s one battery instead of three, it’s supporting one device instead of three, it’s buying one device instead of three and it’s a massive change in flexibility. It’s a bit of a win for end customers who have run large fleets of multiple devices.”

“Customers have taken this into this space as opposed to us selling the story of convergence – they’ve sold it to us more than anybody else,” he explains. Allerton gives the example of the system PTTI provided to Warrington Buses to replace its MPT-1327 system as an example. “We ended up not only replacing the voice service, we also embedded the real-time passenger information service and updated all their on-street stop signs to an LTE-based system, not PMR.”

“We’re driving next-stop displays, we’re doing public access Wi-Fi, we’re doing voice communications and real-time passenger information all from one box…”

Tait’s Bishop has a different take on this. “From a UnifyVoice perspective, our proposition is around leveraging the benefits of the smart device, it’s about increasing situational awareness and the user’s ability to leverage the smart device, so you can do things like picture messaging and you can use the mapping for example to know where your team members are. It’s about a value-added offering rather than a cost-reduction exercise.”

End-users can now opt for PoC in a variety of device form-factors including traditional radio handsets, like the CP-300 supplied by iPTT (left), or rugged smartphones, such as the SYMPOC SY580 available from Syndico (right)

What about MCPTT?
Returning to ESN, the expectation will be that it will eventually run fully standardised Mission-Critical Push-to-Talk (MCPTT) services. The biggest difference between these and their PoC counterparts is that mobile networks that have implemented MCPTT will offer MCPTT device users priority packet data, ensuring that they will get through even in circumstances when the networks become congested for ordinary consumers, and MCPTT is expected to be supported by a range of interoperable hardware from many different vendors.

Tait’s Bishop says he “can’t see there being a business model to provide the level of availability that ESN and other public safety mission critical agreements provide to other users, who today are used to LMR’s level of availability, which is in many cases similar to [that experienced by] public safety.” He adds that the “real challenge” is whether the MNOs implement the relevant 3GPP release and see the commercial case for doing so.

“I’m not seeing the death of LMR [because] of the release of [mission-critical] LTE for that reason [and because] the availability of spectrum for private LTE networks is almost non-existent…it’s there, but it’s leased by operators.”

“We’re going to be developing another system that will conform to the MCPTT standard, but that’s a little bit further down the line,” says iPTT’s Lowery. “Ninety-five per cent of users want just the box-standard day-to-day system. No PTT system in the UK meets the [MCPTT] standard yet because it is for mission-critical users, so it will cost a lot more money. Our system is for private companies, businesses who want to get into PoC, not mission-critical [users]. The level of resilience we have is quite high. It makes us think, why do we want to generate another product just to conform with MCPTT, but you must if you want to be involved in the bigger schemes.”

PoC has emerged like a butterfly from its chrysalis onto the stage traditionally dominated by PMR and addresses many of the issues that mobile and wide-area users have struggled with. That said, it’s up to the end-user to decide if they’re happy to rely on today’s cellular networks rather than a system within their own sphere of control.


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