Firefox OS/Geolocation
This is what I understand to be true about the configuration of Geolocation (A-GPS) on B2G as of my writing. If you find something wrong, or misleading, please fix it. It's wiki after all.
Mozilla does not product Firefox OS images -- we provide source code to chip manufacturers and OEMs. They parties customize various parts and create binary images for devices. The final Firefox OS image is mostly what we is in public source repositories. This is an important distinction because the configuration of some parts (like linux config, device setup, etc) is not in Mozilla's hands.
There are two well known differences between what is on https://github.com/mozilla-b2g/ and what is on commercial phones. The first difference is the RIL (https://wiki.mozilla.org/B2G/RIL). Sometimes chip manufactures replace this code for various reason (Don't ask. I don't know the details other than it's secret sauce).
The second difference is the geolocation component. I also do not understand exactly why some chip manufactures replace our component. I also assume that it's because they know how their chips work and have private apis they are not ready to release.
So, to recap -- some pieces are NOT under Mozilla's control and one of them is the geolocation configuration. It is completely up to the chip manufacturers and OEM to correctly configure a-gps.
Next, the configuration of a-gps is in two parts. The first part is in Gecko. B2G/gaia currently uses supl 1.0 with cell fallback. We have code in our geolocation provider that informs the modem that an agps server is located at a QC supl1 server. We do this by calling an API and pass only a FQDN and a port. The other part that needs to be configured is the “modem”. The modem needs to be configured with TLS enabled and the certificate of the QC supl1 server. Mozilla does NOT have any way to configure the modem and OEMs are encouraged to discuss this with their chip manufacturer. (I am using QC here because as of this writing, that is who where using. If you are using another chip manufacturer you'll have to work with them on an a-gps service).
So, to recap – Mozilla does not ship binaries. Mozilla does not configure Modems. If you are shipping devices, you must ensure that a-gps is configurated properly. Configuration of a-gps is completely outside of the skills and tools that Mozilla can provide.