My iphone 4 bluetooth not working

You can't pair it with a phone or iPod, and you can only pair it with a computer for tethering if you pay for a tethering plan from your carrier and they support the personal hotspot feature.

So you mean if i use a bluetooth dongle with my pc then i will be able to pair with my  pc for tethering?

And i was having one more doubt

Few days back i was trying to pair it with a bluetooth headset but then too it didnt discovered anything

Does there are specific models which are compatible with iphone?

The headset, or any other Bluetooth device for that matter would need to be in discovery mode for the iPhone to see it the first time.  After paired, then the iPhone will detect the device anytime it is in range and Bluetooth is on.

If u read everyone with a iphone 4 or 4s has no luck with bluetooth. It is clearly a fault within Apples ios

Or it is the reciever and transmitter for the bluetooth device. It is Apple not testing their piece of **** device before selling it. So listen up Apple. If you Can fix this issue get off your arses and fix it. Cause im sure myself and many others who have paid for this useless piece of **** the "Shitephone" are not happy. So if its a operating system issue fix it in the next update you so called genius's cause we're not impressed by the pile of **** it is. Not happy! will be the last Apple product I buy. Thanks for worrying about all this other useless **** like Siri and redeye reduction and other useless **** next time test the bloody thing before selling it. Cause bluetooth has been around for what about 10 years. Now. But it doesnt work on this. Awesome work guys NOT!

The iPhone was never designed to be able to connect to another phone or computer via bluetooth. It is not a fault since this is by design.