[Q] Phone Calls do not connect - Galaxy S III Q&A, Help & Troubleshooting

Hi All,
I've been a visitor to XDA for couple years now and greatly appreciate the people who post here who have helped me to custom my Galaxy SI, SII & SIII with generally no issues. I've had my SIII for about a year and a half now running CWM & CF root with either Darky's ROM or a Nightly build of Cyanogen Mod.
Since moving to a new house (few weeks ago) the signal on my handset drops as I make/receive calls. I assumed initially it was just the signal in the area and as I had been running a non-stable build I flashed a full release to be certain. I chose Delta ROM initially but have since flashed Darky's, Delta (again), Cyanogenmod (Nightly, stable, unofficial 11), multiple different Modems when running CM (area specific, model specific & the emergency one for EFSv2) and followed the guide to reset to stock (unroot, official recovery, reset counter & stock ROM) none of which has helped.
To be specific, I can use the Wi-Fi, 3G, send texts and use apps which use 3G to send texts (MightText); which to me (Novice at this stuff) seems to indicate that the 2G & 3G functions of the phone work. Yet still as I make a call, or receive one, I do not hear ringing, person speaking or any form of buzzing; this applies if I use the phone as normal, the speaker phone or a handsfree set.
Roughly 30 seconds into the call the network drops (signal bars go empty), the phone call displays 'Out of Network Area' or some such, the call ends and the phone returns to the home screen where roughly a minute later the network reconnects and I can use 3G again, send texts etc. as above, except still cannot make calls.
I don't know if it has any bearings but on Cyanogenmod the time before the network drops is around the 45-60 seconds mark, all other ROMs disconnect at around the 30 second mark and my GF has an S4, on O2 as well, and the signal on her phone has been temperamental lately, but has not shown the same problem, she is running Stock firmware without root etc.
If I had to replace a component instead of sending off to service centre, how difficult would that be?
Thank you in advanced,
Martin

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If it still has the same issue with full stock rom then it's hardware, motherboard/antenna etc. Unless you often dismantle and successfully reassemble mobile phones it isn't recommended to try yourself.
Samsung give two year limited warranty, worth trying with service centre after resetting counter.
Sent from my GT-I9300 using Tapatalk

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boomboomer said:
If it still has the same issue with full stock rom then it's hardware, motherboard/antenna etc. Unless you often dismantle and successfully reassemble mobile phones it isn't recommended to try yourself.
Samsung give two year limited warranty, worth trying with service centre after resetting counter.
Sent from my GT-I9300 using Tapatalk
Click to expand...
Click to collapse
Yeee I had a look around alot of forums for similar issues but could only find posts where there was no signal at all or playing up due to modem etc.
In desperation I opened dialogue with an O2 Guru who said hardware, but just seemed very coincidental to have happened when we moved =/
Thank you for confirming though worth a shot!
Martin

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You moved so you may not have the same signal strength .
You need to work out if it is the network or the phone .
Try another phone in your location with your sim .
Test your phone next to an O2 mast .
Wipe phone flash stock rom for your network and test .

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JJEgan said:
You moved so you may not have the same signal strength .
You need to work out if it is the network or the phone .
Try another phone in your location with your sim .
Test your phone next to an O2 mast .
Wipe phone flash stock rom for your network and test .
Click to expand...
Click to collapse
The O2 Guru I spoke with said the signal at my home address should be OK, my GF has an S4 on O2 and although a bit crackly, her phone functions works and I have my SIM in a temp phone, a Galaxy Ace, which has also been working fine in the area.
It's a good idea to test closer to a mast, I don't know where the nearest one is to be honest, is there anywhere I can find this out?
My phone is currently flashed back to stock, that's recovery, ROM, counter, modem (I believe) etc. followed this guide to do so:
http://forum.xda-developers.com/showthread.php?t=2323847
What boggles me is that the phone is able to send texts, use 3g and search for different networks to 'register' etc. but the phone call disconnects. I would have thought that the same component which connects to network to send texts would connect to make calls? Is it possible that where I am in a weak signal area, the phone has damaged the component by increasing the gain by too much/for too long? If so is that because there was custom software or would the settings for this component be the same as stock?
Bit concerned about sending it off and the possible questions/costs associated with this sort of thing. This is the first time I've had a phone which has a hardware fault, all the other times a phone has played up its usually due to the software which can be flashed using any number of methods found on this site.
What a frustration, sorry to ask so many questions, just at a bit of a loss as to what to do with it now!
Thanks,
Martin

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In a weak signal area your phone has to output 10x the signal strength to maintain voice call, which it probably didn't have to before. Data and text use much less power, hence why they still work. To test just find somewhere with full bars strength, maximum ASU value in settings, about, status.
It sounds like a high resistance gap somewhere, it gets hotter during use until it breaks the connection - then cools to join again.
Just make sure you describe the fault correctly and it should be repaired.
Sent from my GT-I9300 using Tapatalk

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It's a good idea to test closer to a mast, I don't know where the nearest one is to be honest, is there anywhere I can find this out?
GOOGLE O2 network check see O2 forums .

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Modem
ReFlash modem pls