We have a business VOIP system set up in 3 different locations that allow calls to be made within the network, like you would with different extensions within an office. Currently the extensions are in Philadelphia and two FL locations. We will be adding 2 more extensions in the DR.
The phones look like standard multi-line office equipment with a power cord and an ethernet cable that plugs into a router. The equipment is an Allworx 6x IP PBX and model #9112 phones. Our home base is connected to a business VOIP connection (incredible inexpensive). Internal calls, regardless of where they are located in the world, cost nothing. External calls are very inexpensive (like US$.05 per min. to the DR).
It does require solid, clean upload at nearly 312k (if all extensions were on at the same time, and folks were also on the net), less with a Quality of Service priority system. But the quality so far has actually exceeded either cell or land lines. Hopefully this will continue in the DR, and technically it should with the correct satnet system.