With Nokia 6230, it is noticed that security authentication procedures (link key exchange) are invoked during each connection attempts, even with paired devices.
This could be checked by first pairing a local bluetooth device with 6230.
Later remove 6230 from the paired device list at the local side and attempt connecting to 6230. Remember not to remove the local device from the paired list of 6230.
6230 will again initiate a pairing procedure.
Other phone models including Nokia 6600 does not have a similar behaviour.