I have the OCNA issue too with an iPhone 4S 64GB white. The iPhone was bought in UK. From the serial number it was made in China, Chengdu, Foxxcon, in the 45 week (November) of the 2011.
My family have another two iPhone 4S too, but these aren't affected by OCNA.
From the serial numbers, one in black with 32GB was made in China, Chengdu, Foxxcon in the 48 week (december) of 2011, the other one in white with 64GB was made in China, Chengdu, Foxxcon, in the 42 week (October) of the 2011.
I live in Italy and I use Vodafone.it as carrier. I tried to restore the iPhone, but it doesn't work. Bluetooth and SIRI are disable. Only if I active speaker on-off I can make ALL calls.
I'll try to use IOS 5.1 b3 to see if it work for me.
After 2 days of going back to 5.0.1, and the observation that problrm occurs more when using Viber, I installed sbsettings, and used kill processes after terminating Viber, I notice that the phone is good again and working well with my car bluetooth. So I wonder if multiple dialing programs ( not necesserly viber only ) has an effect on this issue. Actualy I srongly believe so, as i have been testing it and phone works well when viber is not used or its process is killed and memory cleared.
So my advise for people who cant exchange their phone, install SBSETTINGS and Killbackground, and do frequent memory clear from sbsettings and dont leave programs running in background.
This will allow you to use you hands free devices and you phone and enjoy them
Ok, so popping in a sim might have "fixed" the issue for a bit but still ran in to the same problem.
Went to an Apple Store and got a replacement one. So far it's working well.
Initially, the tech said it's a software issue and that he'd have to wipe the phone and I couldn't load my backup coz that's the cause of the problem. I couldn't believe it.
Anyway, I obliged and agreed to wipe it, tested it after and still the same OCNA issue. Red to his face, he begrudgingly replaced my iPhone.
Terrible customer service. Almost worse than pulling teeth.
The only good thing is I got my phone replaced.
Just for record this problem dose not effect on 3rd party applications like skype, viber or what else, because they use the WIFI or another data communication protocol, when you make a normal call, the GSM modem and phone mainboard and other sensores involved in this operation and switching between these objects makes the problem. then you can not compare that application activity with normal making calls ( the basic and fundamental phones functionallity)
I have the same problem with no audio on outgoing calls (iPhone 4S, 32GB, black, bought in dec-2011) in Orange Slovakia network. I just put the phone back to Orange for a repair.
From my experience, the frequency of the audio outages seems to vary widely. I had a time when I made 15 calls without any problems and then 5-7 calls in a roll with no audio. Sometimes each second call had no audio. I also tried to make calls with something close to the proximity sensor and calls without anything close to the sensor. Nothing seems to help.
To finish my story: After a week I got a new phone. BTW, great servis by Orange Slovakia, I was really surprised. I thought that the answer from them would take 30 days with result that they were unable to replicate the problem and I will get my old phone back. Nop, I have a new phone and so far (after approx. outgoing 50 calls) no problem with OCNA.
@gibovo - many thanks for the contribution
0. GSM calls affected ONLY. Problem is not applicable to VoIP calls (Viber, Facetime or simiar).
1. iPhone 4s AND iPhone 4 with iOS 5.0.1
2. iOS 5.0.1 mostly, but there are some reports for 5.0 and 5.1b3. NOT all phones 5.0.1 are affected.
2a. AFFECTED (some examples)
64GB white, China, Chengdu, Foxxcon, 45 week
2b. NOT AFFECTED (some examples)
64GB white, Chengdu, Foxxcon, 42 week (October) of the 2011
32B black, Chengdu, Foxxcon, 48 week (October) of the 2011
3. 16GB/32GB/64GB ALL potentially affected (see examples above)
4. black/white ALL potentially affected
5. operator RANDOM/ALL
6. country RANDOM/ALL
Disable/Enable bluetooth, try to make a call. (for me this works 100% of the times)
Second call/ speaker on-off MAY help (this doesn't work always).
Disabling Siri and Bluetooth may help to face the OCNA symptoms less frequently.
Can we make a poll on this Forum? This would help get to the common criteria much faster?