On 12 August 2016, Obihai placed the OBi100 and OBi110 under "End of Life" status. This means they would devleop no new updates for these devices.
In late 2017, Google updated the Google Talk server certificates. The new certificates were incompatible with the ones contained in the OBi100/OBi110 firmware, so these ATAs ceased to function.
Shortly before Christmas 2017, Google reversed their changes, causing many OBi100/OBi110 ATAs to start working again. However, a user who (constantly) claims to be close to Google staff says this is not permanent. So, several users on the DSLReports VoIP Tech Chat forum discovered how the firmware could be reverse-engineered and updated so that future changes made by Google will not cause the ATAs to stop working.
Besdies Google Voice on OBi1, some other useful features have been added. The new firmware allows Google Voice to be configured without the OBiTALK portal. Firmware updates have also been developed for the OBi2/OBi3 series which adds a SSH server, and allows the OBi3 ATAs to be configured with Google Voice(!)
If you don't use Google Voice, don't worry. You don't need to change your firmware. The changes made by Google only affect users of Google Voice.
Not any more. Some very intelligent users developed a firmware that is a direct replacement for the official firmware and can be easily installed using traditional methods.
These firmwares, like the official Obihai firmwares, are provided without warranty. Standard precautions apply, such as do not install firmware over a wireless network connection.
Advanced users: do you want to patch your own firmware? First find and download BsPatch, the official firmware, and the bsdiff file from DSLReports. Then run something as this:
bspatch OBi1-1-3-0-2886.fw OBi1-1-3-0-2886-naf7.fw newcerts7.fw
DSLReports hosts one of the busiest VoIP forums on the internet, which is the forum where this firmware was first discussed and published.
The OBiTALK Community is a forum specific to users of OBi products. It has largely been abandoned by Obihai but the users are sometimes helpful.