Southernlinc is a niche wireless provider with a 127,000 square-mile regional coverage area that includes Georgia, Alabama, southeast Mississippi and northeast Florida – now that’s niche. In addition to their regular plans they do have a couple of prepaid plans - almost like a southern version of Revol Wireless except smaller.
As noted above, it’s a local wireless provider. Make sure you are in Southernlinc coverage area. Unlike some regional but growing providers, they don't seem to be promoting their growth ambitions.
Their phone (one model) comes as part of their Prepaid Bundle Package. In the package you get a Nokia i290, charger, 64k sim card and $10 worth of airtime. The package costs $49. The terms of service agreement does state limitations on what other phones you can use, so presumably you could try using a phone you purchased separately.
Otherwise, they carry a wide selection of phones for their contract plans including several rugged models that are certified as Mil Spec (military spec).
There are two daily plans and one monthly plan.
Their lowest daily plan charges $1.25 on the days you use it. In addition to the daily charge, talking costs 10 cents per minute and text messages cost 10 cents each. You can add to your airtime in three ways: 1) via the phone by dialing #ADD (#233) and entering your credit, debit or prepaid card, 2) online and 3) at a local Western Union office – presumable you give them cash. Minutes do not seem to expire, but your account cannot be inactive for more than 60 days. You can check you balance by dialing #BAL.
The unlimited daily plan cost $2.50 on the days you use it. On those days you get unlimited calls and texts.
Their monthly unlimited plan costs $50 a month for unlimited calls and texts. This is a better option if you use the phone every day for a significant number of minutes.
You also have access to "push to talk" service. I assume this would help you save on your airtime if you tend to primarily call someone else nearby who also has the same plan. If you're in their coverage area and don't move around much, you might give them a try.