First, let's talk about your connected fleet. Did you know that you can pair your mixed fleet with GM's OnStar? Verizon Connect, Spireon's FleetLocate,MapAnything, and FleetComplete all work with the existing OnStar hardware -- making it easy for you!
Now for the rest: the ELD mandate has people scrambling for options. Those who do interstate travel probably already have them, but some people didn't need the DOT before because they are just now growing to out-of-state work. Where to start? With the plethora of options available, let's look at a few simple ones below. BUT FIRST, here's a video on what ELD is and how the Weigh Stations and traffic stops could use: https://www.youtube.com/watch?v=NzrHs_4dEk4
1) When it comes to cost, Bit can't beat: No monthly service charge, so when you have a smaller fleet and don't need to check on them, this could be a simple solution. http://eldratings.com/blueink/
2) One of the big third party players out there is Geotab. I've heard many people that use them and like them. What I really like about them is that they make news with their improvements -- including their Third Party Device plan that allows you to view all your fleet in one screen if you use additional providers. For example, let's say you buy a new truck and they provide a trial period of their ELD service. You like Geotab, but decide to use that trial period. With the 3rd Party Device plan you could integrate that new truck into the same screen you already view (instead of switching around through multiple webpages and sign-ins). https://www.geotab.com.
3) Integrated telematics have ELD options available, too. What are integrated telematics? It's a system that is already hard-wired into your truck from the factory. An example of this would be Verizon Telematics (formerly known as Telogis, Fleetmatics, and others before being merged into a unified name)
There are many out there, but between these three alone you should be able to get started on your journey. Happy motoring!