I faced this issue twice, on 2 different ZTE OpenC FR devices. Both have been rooted with the ZTE tool, and installed with the 2.0 community build, dated 20141123 (http://builds.firefoxos.mozfr.org/doc/fr/devices/zte-open-c-fr#telechargement) What happened : - a phone call is incoming - the device rings - the user tries to answer the call - the devices hangs with a completely empty white screen - the phone does not respond to anything (screen or buttons) - only one solution : remove the battery and reboot The white screen looks like the one in this video : http://youtu.be/V8-r6hRXkH4 (but it did not happen while browsing : it was when picking up an incoming call)
This issue is hard to reproduce : it happens very rarely. Could it be a bug in the low-level layers of the phone, that has been fixed in the B03 build of ZTE? See the changelog in http://www.ztefrance.com/assistance/#faq (choose "Open C" -> "Questions fréquentes" -> "Version logicielle") : La version FFOS_FR_ZTE_OPENCV1.0.0B03 (disponible mi-Octobre 2014) apporte les améliorations suivantes : 1) Correction d'un bug provoquant des redémarrages intempestifs lors des appels (...) (translation : the B03 version fixes a bug that reboots the device on an incoming call) If I understood correctly, the community builds use the low-level layers (kernel, gonk) from the root tool of ZTE (which is version B02, not B03)
It might be a duplicate of bug 1017604. I did not face it for a long time, but maybe I've just been lucky?
This issue seems to be specific to the ZTE Open C device. It seems to be fixed in the official 1.3 B03 version of ZTE, but not in the community builds (because they are based on a 1.3 B02 rooted version). I close this as invalid in this bugtracker. The issue is tracked in https://bugzilla.frenchmozilla.org/show_bug.cgi?id=608