If the phone is not "seeing" the device, then it appears the device is not in discovery/pairing mode. What does the use guide for the device say that you have to do to put the device into pairing mode. That needs to be done, preferably with the Bluetooth in the iPhone off, then once the device is in discovery/pairing mode, turn the Bluetooth in the phone on. This will put the phone in discovery/pairing mode and it should be discovered.
Thank you for reply, but don't mind. I have written this thing about HC-05 Bluetooth Module in the hope, that may be a developer see it and checks this issue for the next patch.
The device is fine and it's pairing mode is ok, since ios6 sees it and also it is visible on my 3 own development devices with andorid 4.0 and 4.1 running on it. So my conslusion is that is definitely the ios upgrade, which cause the issue. However to make me sure, i have just tried to do it like you have written with turining off BT on iphone, starting device and then bt again - unfortunately again with no result.
Well, I don't believe you will see too many developers here in the regular forum, and if you are not a developer, you cannot get access to the developer's forum.
I do not share your assumption that it is a universal iOS update problem. I have had no issues with my devices, nor has anyone had with theirs either. While you may have read some Bluetooth problems, most are being corrected when they attempt to pair the devices again. I do not believe an iOS update is going to correct your issue, as iOS updates will generally result in Bluetooth updates to greater levels, not improve older ones. It just seems to me if it is being discovered in iOS 6, it could just as well be an incompatability in your device. Have you tried to pair this iPhone with anything else to be sure the Bluetooth of the phone is defective?