First of all, the Nokia 2600
is not a blue tooth phone.
If you should get a Nokia phone that supports blue tooth your best bet would be to make sure any previously paired devices are turned off.
Then make sure that blue tooth is enabled on your phone. For most Nokia models its as follows;
Menu > Settings > Connectivity > Bluetooth > Bluetooth On
Then attempt to put your device in pairing mode.
... > Bluetooth > Search Audio Enhancements
If your phone supports Bluetooth the phone should and device should pair after you enter the pairing pin, usually 0000.
Johnny_Nh, to answer your question, different Models are equipped with blue tooth when they are manufactured. Also, there are different versions of bluetooth, 1.0 and 2.0. If you have an older phone supporting Bluetooth 1.0 you will not be able to use a bluetooth 2.0 headset.