The picture above describes an arrangement, where part of the remote sites is connected over a private UHF/VHF radio network (e.g. sites requiring 99.9% availability) and the remaining sites are connected over a cellular public network (very remote location, but with a good cellular signal).
The SCADA Center can be connected either to central RipEX or even to M!DGE, both can serve as the Master unit. Please see the following example of one possible settings. M!DGE units use the private APN with static IP addresses.