We live in an era when phones often support a dozen or more LTE bands, making them functional on virtually all carriers. Simply working on a carrier might not be enough anymore. There are advanced network technologies like VoLTE and WiFi calling that require device makers and carriers to collaborate to test and certify phones. The GMSA has taken note of this clunky process, and is now working with its partners to develop an open standard for delivering carrier features to more phones.
Currently, there's no guarantee an unlocked phone will have VoLTE and similar features when you pop in your SIM card. If the device maker didn't include the necessary carrier files in collaboration with the network operator, you're just out of luck. The GSMA wants to fix this by launching a "Centralised Device Settings Database." This online repository would be run by the GSMA, allowing carriers to upload universal device settings. When you insert a SIM card in a phone with support for this system, it would grab the necessary settings from the database (probably going through the OEM) to enable video calling, VoLTE, WiFi calling, and so on.
As a user, this means you could have access to advanced network features on more devices. You would not be limited to branded phones or select unlocked devices that have your carrier's blessing. The open standard should also be cheaper for both carriers and OEMs. Carriers wouldn't have to test each and every phone, and OEMs wouldn't have to integrate multiple carrier files into the ROM. It's a win for everyone.
Thus far, several dozen device makers and carriers have gotten on board with the Centralised Device Settings Database. They include AT&T, Verizon, Three, Vodafone, Samsung, LG, and more. This is all still in the planning phases, but it sure sounds neat.