This is quoted directly from AvPlan's website.
"Cellular based traffic solutions such as AvPlan Live help to bridge the gap where ADSB-in is not available. These systems rely on an EFB sending position reports to a ground system periodically and that ground system sending back known traffic. The update rate for these system is generally very good, but rely on having cellular coverage in the aircraft and users using the same EFB product. For GA VFR and RA aircraft, these tend to fly at lower levels where cellular coverage is usually better, alleviating some of the issues with cellular coverage.
Cellular systems currently only depict aircraft using the same EFB product. Since the introduction of AvPlan Live in 2015 we have been willing to share traffic data on a reciprocal basis with the other main EFB vendor in Australia, but they do not wish to enter into such an agreement. If this policy were to change, data could start to be exchanged in a matter of days. It is not difficult or expensive to do.
Our cellular based traffic system, AvPlan Live, also includes feeds from ground based ADSB and FLARM receivers. Traffic received by these ground units is also displayed on AvPlan EFB. If you also have an ADSB-in receiver, the traffic via the attached device will replace that received from the ground."