The iDEN Network Turndown – what it does for LTE.

The turndown of the iDEN LTE network now allows Southern Linc to use its entire spectrum for the CriticalLinc LTE network. The dedicated spectrum will deliver benefits to both existing and new LTE users.

"We've had a foot in two camps for the past four years or so, maintaining both the iDEN network and the LTE network," says Alan McIntyre, Southern Linc's Engineering Director. "When we shut down the iDEN network completely, 100 percent of our focus will shift to maintaining and optimizing the new LTE network. From an ongoing networking, operational, maintenance and service perspective, we'll be laser-focused on LTE."

Timeline for the turndown

Southern Linc went through the process of suspending service on thousands of old iDEN phones during March, but not all of the network elements were turned off. When all sites are turned off, new software will be pushed to more than a thousand LTE cell sites across the 4-state footprint, allowing the CriticalLinc network to utilize the full spectrum available to the network.

Performance improvements will be noticeable

Even though users will likely experience no disruption in service, there will be significant performance improvements that may or may not be initially evident.

"The spectrum that Southern Linc is licensed for is presently divided between the iDEN network and the LTE network," explains McIntyre. "Roughly two-thirds of the spectrum view is used for iDEN, and one-third is used for LTE, so once we're able to turn iDEN down and go all-in with LTE, we can use all of that spectrum for LTE. The capacity of the LTE network will then more than double, and that means additional capacity for more data applications."

Ongoing optimization

The shift to an all-LTE network will also allow for a single-focus network optimization and performance improvement.

"We placed LTE test equipment in all of our site technicians' trucks, and we have a team that's dedicated toward optimization as well," explains McIntyre. "Our test equipment collects data as our teams drive around the service area. We use tools that analyze the data so that we can make software changes to the network to help improve performance in a given area. A lot of optimization happens through the lens of a user's experience, so we're trying to optimize to greatly reduce dropped calls, any kind of garbled audio and any issues that really impact somebody's use of our LTE services."

Understanding the difference between Linc PTT on the CriticalLinc network and Linc PTT on another carrier's network.

Your XP5s and XP8 mobile devices are the best options for running CriticalLinc's mission critical Push to Talk (MCPTT) service, but now your co-workers using other carriers can get the Linc PTT app to communicate with you via PTT. The Linc PTT app is now available on both the Apple App Store and the Google Play Store. This application is more limited than the full-service offering experienced on the CriticalLinc network, but it enables essential two-way radio communications to any Southern Linc phone using Linc PTT, as well as any other phone that has the Linc PTT app enabled.

"The SONIM XP5s and XP8 devices still provide the best PTT experience, because they are purpose-built for the needs of our customers with built-in technical and software features and enhancements to make them perform better on the CriticalLinc network," says Ritesh Desai, Product Engineering Manager. "That said, this is a great option for our customers who also carry other carriers' phones, but want to stay connected with work teams."

Here is how Linc PTT features and benefits on a SONIM device compare with the Linc PTT app for other carriers' devices:

One-to-one PTT Calls



PTT Call Alert



PTT Group Calls



Group Lists



Talk Group Scan



Priority Group



Personal Talk Groups



Emergency Alarm and Call* (high performance feature)


Not Available

Linc Message* (high performance feature)


Not Available

Linc Map* (high performance feature)


Not Available

Audio Quality


Carrier Dependent

Audio Strength


Carrier Dependent



Carrier Dependent



Carrier Dependent

PTT Button

Dedicated Button

On Screen


Included* in all CriticalLinc service plans

$15/month per line to existing CriticalLinc customers

Network Resource Priority


Carrier Dependent

* High performance features carry an additional charge for use on the CriticalLinc network. These features are not available on other networks.

Understanding Talk Groups and Group Lists

Questions and Answers from the Pros

We all know the benefits of having a single conversation with a group versus having that same conversation multiple times with various individuals.

Now, Linc PTT Groups and Group List functionality can save you the hassle of digging through individual contacts or various groups, so you can have seamless communication with the groups you need, when you need them.

What's more, the Linc PTT Group List feature allows you to monitor up to 10 Enterprise MCPTT Talk Groups at a time, making it easy for you to monitor multiple groups and ensure you won't miss out on important updates you need to hear.

Sound interesting? Here's a quick Q&A to get familiarized.

Ritesh Desai, Product Engineering Manager, walked us through a few of the highlights, benefits and features now available.

Q: In general, how do Personal Groups work?

With the Southern Linc CriticalLinc LTE network's MCPTT functionality, you can potentially set up hundreds of Personal Groups made up of individuals that you select to be part of that group. It's very easy to do from the Linc PTT app. Simply tap on 'Contacts' then, touch the 'People' icon in the bottom ribbon. A list of available PTT Contacts appears. Touch the selection box at the right of the name of each person you want to add to the list, touch the 'floppy disc' icon in the lower right of the screen, then name it and save it. This list will now appear in the Contacts tab of the Linc PTT app.

Q: What's the difference between Personal Groups and Group Lists?

While Personal Groups are made up of selected individuals, Group Lists contain multiple Enterprise Groups that are pushed to your phone by your company. You see them when you touch the 'two radios' icon in the ribbon near the top of the Linc PTT app. You can create 10 lists of Enterprise Groups on your phone, and then you can scan a selected list of 10, at one time. In order to do this, you must place your selected Enterprise Groups into a Group List and then turn on the Linc PTT Scanning feature for that list. You cannot place a Personal Group in a list of groups – only Enterprise Groups can be placed in a list. This helpful video shows you more about creating lists and scanning groups:

Q. What's the greatest benefit of using Group Lists?

While having dozens of Enterprise Groups may be useful, using or accessing all those groups at the same time is not very effective. Most of us are only interested in certain Enterprise Groups at certain times of the day or even in certain situations. So, the idea behind Group Lists is that you can build customized lists of groups for various reasons or functions. For instance, you can build an Enterprise Group List for when you are in the car or when you're at work. When you select a particular list of groups, it is the only set of groups that your phone monitors. So, the Group List feature helps you narrow down the groups you listen to and allows you to quickly change lists as you need to. (If you do not have any Enterprise Groups in your Linc PTT app, you cannot use this feature.)

Q. What recommendations do you have for users? Where can you find more information?

Group Lists allow you to instantly communicate with a large group of people at any given time. You have the ability to reach out to them, and they have the ability to reach out to you. So, it's important to consider building Enterprise Group Lists for the role that you're working in, and especially if you have a more dynamic job that holds many roles, then Group Lists can be very helpful and efficient to create in order to help you in each of those roles. What's more, it's very easy to set up on your phone. The CriticalLinc Knowledge Center has PTT tutorial videos for the XP5s and XP8. That is a good place to get more information.

Fleet Management - do you know where your assets are?

If you're a fleet manager, you understand the importance of knowing where your vehicles and assets are at all times. In fact, your organizational success is directly tied to the effective management of your fleet and your assets.

That's why so many fleet managers are excited to learn about Southern Linc's new Silent Passenger Fleet Management Solution offered to users of the new CriticalLinc LTE mission critical network.

This flexible, highly configurable vehicle tracking solution lets you bring state-of-the-art vehicle location services to your fleet, improving fleet management and increasing efficiency while reducing costs - all at the same time.

How it works

The Silent Passenger Fleet Management Solution is a powerful enterprise software system that uses GPS and wireless technology to enhance the management of both vehicles and drivers.

The solution's standard features are designed to provide you with the most essential mobile services to help get the most from your fleet management, like mobile GPS location tracking, detailed maps, speed and stop time alerts, geofencing and landmark alerts, real time traffic with ETAs and detailed reporting. A second-tier offering provides even more benefits with options like split screen functionality, fleet-configurable driver scorecards, vehicle diagnostics and more.


One of CriticalLinc's key benefits with Silent Passenger is its ability to integrate with existing systems for public-sector organizations and businesses of all types, sizes and verticals. To start, it can be integrated into your fleet equipment either with the Sierra Wireless GNX-6 tracking device or it can be used on our Sonim XP5s and XP8 handsets, giving you the power to track what you want, when you want it.

Even better, third-party integration capability allows you to leverage fleet management data with existing back-office systems to provide you with a holistic view of departmental or company operations.


The fact that the system is completely configurable to fit the unique needs of each client is a definite plus for fleet managers. A menu of desirable modules, like SP Speed or SP Fuel Management (see full list below), allows you to select the services you desire without having to pay for unwanted add-ons.

Cost Effective, Value Add

With Silent Passenger through CriticalLinc, you get a low-cost, high-value cloud platform that is central to effective cost management along with industry-leading 36-month data archiving, providing long-term recordkeeping for fleet compliance. Learn more about all the Silent Passenger options at

CriticalLinc Data - Linking up with tough.

Panasonic ToughBooks, Getac Tablet now in use on the CriticalLinc Network

The Panasonic Toughbook and the Getac F110 Tablet are now being field tested on Southern Linc's CriticalLinc mission critical LTE network, leading the way to greater possibilities and data options for Southern Linc customers.

"The fact that we have customers in the field using these devices is big news," says Connie Stinnett, Senior Market Sales Executive. "Now that we have our new mission critical LTE network that can be depended on for critical data, we're starting to see more doors opening for customers to integrate with some of the best tools and resources on the market today."

The Panasonic Toughbook and the Getac F110 Tablet are industry leaders for rugged, purpose-built devices with reputations for withstanding even the toughest environments and most demanding or extreme situations, such as with military personnel, the public service sector, law enforcement, emergency medical services, and more, while providing an exceptional user interface and user experience.

The Toughbook and Getac devices are currently being tested with the Huntsville Police Department. With both, the devices are tested using Southern Linc's LTE SIM card within the devices, allowing personnel to accomplish all their work - monitoring calls, deploying assets, issuing tickets, looking up data, and more - using the CriticalLinc network.

"The testing is going very well," says Stinnett. "We're expecting several hundred units in this installation once testing is complete. We expect to see even more integration and opportunities utilizing the new LTE network in the months to come."