Anyone have any experience with them?
I'm guessing the network is Sprint, not Verizon?
The $14/mo. (taxes???) (Unlimited/Unlimited/10gb) plan seems good value but maybe other Sprint MVNO match/beat it?
Edit - Their about us mentions cintex wireless, I found this post
https://www.nthcircle.com/forum/search?query=Cintex&searchdate=all&childforums=1
FWIW: I purchased the Liberty Wireless $60 eBay one year unlimited talk and text plan about 6 months ago (T-Mobile network), which has worked fine so far. Cintex and Sfone, and others, have HTH Comm as their parent company. My Sprint phone was deemed eligible on the Sfone checker, whereas my GSM phones were not, so Sfone appears to use the Sprint network. However, this SD thread says both GSM and Sprint phones should work on Sfone.
"HTH is a parent company of:
NewPhone Wireless – NewPhone Wireless provides government-subsidized mobile phone service for qualifying low-income consumers through the Federal Lifeline program. Visit www.newphone.com to learn more.
VTel Wireless - VTel Wireless provides government-subsidized mobile phone service for qualifying low-income consumers through the Federal Lifeline program. Visit www.vtelnow.com to learn more.
Cintex Wireless - Cintex Wireless provides government-subsidized mobile phone service for qualifying low-income consumers through the Federal Lifeline program. Visit www.cintexwireless.com to learn more.
SFone Wireless – SFone Wireless offers affordable plans and no-contract wireless services for all needs and budget on the Nation’s Largest and Most Reliable Network. Visit www.sfonenow.com to learn more.
Softel Technologies - The Nation's Top Wireless Distributor!
Softel Technologies is the industry-leading Distributor for Prepaid and Lifeline providers. Softel provides extraordinary customer service at the lowest cost and has been one of the largest Wireless Device suppliers to its Master Agents. Visit www.softtels.com to learn more.
Definitely Sprint, based on what I can get to clear their BYOD test page. (The legacy Sprint network at this point.)
Thanks for pointing out the Cintex connection! SFone's 'About Us' page gives lots of useful info about the company's sister connections, which seems unusual for most 'About Us' pages. In my opinion, the connections listed there are probably reassuring as to the viability of SFone, with sister companies including MVNE and LifeLine companies, which might make one more comfortable with how prices can be low, and with a customer base (spread across the multiple entities) that is larger than a typical new MVNO entry. (There does seem to be a connection to the parent and sister-companies of Liberty Wireless, another recent MVNO offering.)
I think $14 is unbeatable for a comparable plan. I see it's marked as "Limited Time Offer", so it would be nice to know that it's not a teaser rate that will go up in price in a month or 3.
A couple of observations:
The BYOD page is picky, awkward, and not very smart.
It will only accept HEX MEID, not DEC MEID or IMEI. (By comparison, Ting or Tello checkers will accept any version of the ESN, and convert back to whichever they're actually using to check databases.)
The error messages for failures are not descriptive.
The large-font entry field makes it difficult to realize that anything longer than 14 digits is being truncated (which would be a good indicator that one must use the HEX MEID), and that it fails to remove a leading blank digit (if copying and pasting), leading to failures because of the string exceeding 14 digits.
I got several phones to clear the BYOD test, including an older Boost Mobile (legacy Sprint), an older Sprint retail (CDMA only), and a factory-unlocked multi-carrier Moto G4 Play. I also had several unexpected failures of other Sprint network test devices, but didn't follow up to try to figure out why they were failing. None of the GSM-only IMEIs I entered would clear the checker. (I'll have to follow up on reading the link Isamorph supplied indicating it's possible.)
SFone supplies SIMs at no charge with an order. Again, it's not descriptive as to which SIM is required, and I didn't see a way to decline the new SIM and re-use an existing SIM. It surprised me that it didn't balk at supplying the SIM for my really old Boost Mobile phone, which the local Sprint corporate store didn't have in stock a year ago.
Their store page has pretty good prices on lower tier refurbished phones, if someone is starting from scratch. (But they're probably refurbished legacy-Sprint devices, with a limited useful lifespan.)
According to their website the price is locked in forever with autopay. Chat has options of 3 different companies, SFone Wireless, NewPhone Wireless, and Cintex Wireless.
re: GSM on SFone. I cannot find any mention of GSM being a possibility, other than in the original post in the link Isamorph provided for the Slickdeals thread. Without further confirmation, I think this is incorrect, and SFone is legacy-Sprint only. (That jives with what both Isamorph and I have seen rejected in the SFone BYOD tool.)
That will obviously change, sometime in the future. (Either SFone will disappear with the legacy network, or they will enable T-Mobile network service.)
Per chat, today:
Hotspot or tethering is not included. They do offer dedicated hotspot plans.
The current 'Limited Time' offers will be available through 10/31, but the rate is grandfathered as long as you keep the line active.
The standard rate plans do not look intriguing.
Did you happen to ask if taxes are included or not in the $14?
I didn't ask about taxes, or about the possibility of GSM. 
Chat said no shipping or activation fees.
I gave a zip code but they could not generate the added amt. total for tax/fees.
Chat said to expect $2-$4/mo. so, if true, it doesn't look like they are playing any excessive or hidden fees game.