I bought a G510 primarily as an Android based WiFi SIP (VOIP) phone but never has a device given me so much grief in setting up VOIP.
When using a SIP softphone with the stock Huawei ROM the mic is either silent (e.g. Linphone) or heavily distorted robotic static (e.g. CSipSimple). I think it may be dual mic related but it doesn't quite match the symptoms reported by others. This problem also doesn't effect regular phone calls, the voice recorder or Google voice search.
A post on here somewhere by someone with the same problem led me to ShockeyCzT's modified stock ROM. His ROM does indeed fix all SIP problems but is otherwise quite buggy.
Then I tried joestone's CM 10.1 ROM. The forum post mentions disabling dualmic so if my problem is dualmic related then this ROM may address it. However for some reason with this ROM I can't get my SIP registration to stick. It either unregisters as soon as I make a call (CSipSimple) or refuses to register at all (Linphone).
Finally I came here to Dazzozo's CM 10.2 ROM. Despite being the youngest ROM it feels like the most stable but it has the same SIP/VOIP problems as the stock ROM. I tried adding "ro.config.dualmic=false" anyway but it made no difference and often causes the entire OS to crash and reset.
So has anyone managed to get a proper SIP softphone to work on the G510 in a stable ROM (preferably this ROM)? I'm out of ideas at this point.