Republic Wireless is one of the many MVNO's that run on Sprint's network. One could say that is a big reason that Sprint's network isn't doing so well, way to many people on it. Republic Wireless is unique though. Instead of just giving you 3GB of high-speed data like Boost Mobile or Virgin Mobile would do, Republic Wireless keeps you on WiFi as much as possible, and has you get onto Sprint's network only when needed. Because of this, all your calls, text messages and such are being done over an internet connection.
Currently, if you make a call on 3G or 4G LTE, and walk into your home where the phone would connect to WiFi, the call will not drop.What Republic Wireless is looking for here, is to see how feasible it is to transfer from 4G to WiFi. The company also says that this project won't make calls drop either, which is always a good thing.
Project Salsa aims to make it easier, and seamless to have calls transfer from WiFi to mobile and back to WiFi without any issues (also mobile to WiFi without any issues). While there's no set timeline for when this feature will be available, Republic Wireless is working on it, and hopefully we should see it soon.
This comes just after the company rolled out their new data plans, where you get a refund for the data that is not used. Similar to what Project Fi is doing, for those that actually have an invite. Republic Wireless has a few other goals that they are working on after Project Salsa is completed, which includes offering newer phones (currently you cannot bring your own phone. Partially because it's a CDMA network, and because it is set up differently, to prefer WiFi all the time). They are also looking to allow their customers to be able to access messages across multiple devices. Which is going to be a pretty interesting feature. Hopefully this will mean you can access your messages on laptops and such as well. We'll have more information as soon as Republic Wireless makes it known.\