I have repaired 7 iPhone 4 & 4S's today. All required the battery to be removed and then replaced after the repair. 3 of the phones powered up as normal and the network signal displayed as normal, they all tested ok for text and calls. The other 4 phones powered up but showed 'searching' in the network signal display. All the phones that showed no signal were on OS6, all the phones that picked signal up were on OS5. Before OS6 was introduced I never had this problem. It wasnt a problem with the aerial or aerial connector as these were checked plus one of the repairs was a simple battery replacement. I tried resetting the 'network settings' and the 'factory settings' and resetting using the power and home buttons, this made no difference. After several hours 2 of the phones picked up signal and within 15 seconds had full signal. I noticed the following which may or may not be relevant. 3 of the phones would accept texts but not calls. When the phone was dialled up the phone that was calling could hear the ring tone when you would expect voicemail but the dialled phone didnt display anything and didnt ring. If you tried to call a number from the phone it would not connect and when you tried to end the call the screen displayed ' call ending' until the phone was turned off (during this period all the other functions of the phone worked). I am sure other people and repairers must have had the same problem as it has happened to all the OS6 phones I have repaired over the last few days, the only exception was a jailbroken phone running OS6 Can anyone explain what is happening or how to get around the issue so that the phone shows proper signal in a reasonable time ?