Hi,
I want to use Arduino to detect bluetooth devices without pairing. The application for me would be to check, if a phone is present within bluetooth range then turn ON a signal. The application would know what the bluetooth ID of that phone would be but it doesn't need to be paired.
I read some articles and came across HC-05 bluetooth shield. Any suggestions on the solutions would be helpful.
Probably not possible and a probably pointless endeavour. This may be because you are a victim of your own technobabble, and don't understand what pairing is. Pairing is essentially a preliminary procedure to facilitate connection. I don't think it would be too hard to have HC-05 constantly poll a known group of phones to test proximity and make, and proclaim, a temporary connection. Thia might be a better job for a BLE device.