I will speculate on pattern at the end of this post, but my BV9500 has alway, since day 1, had this issue where suddenly it will not ring or give notification sounds. Alarm sound still works (thank god) but no ringtone or notification sounds randomly. A reboot causes all sounds to work again, until the issue occurs again.
--what i have tried--
1. I thought perhaps the issue was sound files not showing up on my sd card (perhaps sd card problem). So i switched to stock ringtones and even removed my sd card for a few days. The problem still occurred.
2. While the random no-sound/muting was happening, I tried changing the volume. Both with the volume keys and with the settings menu item to adjust the volume. Both show volume change, but still no sound. Vibrate only.
3. While the random no-sound/muting was happening, I tried changing the ringtone from anything to anything. The preview ringtone that occurs when changing the ringtone worked. but upon the next call, no sound. Only reboot to fix.
--What i have noticed--
When going back and forth from bluetooth connection, this seems to occur. 3 different bluetooth headsets, all of them with a power switch. I just turn them off and put them in my pocket. Whichever one i am using that day. However, sometimes, while i have bluetooth connected, sound works. Then when my headset is powered off, ringtones and notifications have no sound. Then when i reconnect my headset, sometimes, sound!
I speculate this is the driving of the problem. I cannot be sure. But even sitting here right now, no sound. My phone will vibrate. but no sound. I can record this with another phone. All volume is up. ringtone is set. but no ringing, and no notifications.
--something else i noticed--
When unlocking and locking the device, under normal circumstances, the device has a sound. Both for unlock. and another sound for lock. When this problem occurs, the unlock makes no sound. But lock makes a sound. Repeatedly, no sound on unlock. Just silence, but locking makes the chyme lock sound.
These are all the things I can provide for now. This has occurred since I got the phone. i have no other issues. Alarm sound works. but Ringtones and notification sounds stop working and will not "permanently" return until the device is rebooted.
I did go through and "forget" all my headsets, and ran for an entire day, but the audio issue still happened. Just odd that pairing a headset causes the sound to possibly return.
Any assistance would be appreciated.