Since iOS 9.1 update pairing without bonding is not any more supported by iOS. Calling this API command without being in bondable mode, will cause the connection to fail with devices running iOS 9.1 or newer.
Before using this API command with iOS9.1 or newer you must enable bonding mode with command Set Bondable Mode and you must also set then bonding parameter in this API command to 1 (Create bonding).
Bluetooth Knowledge Base
[Deprecated] KBA_BT_1503: iOS 9.1 with respect to Bluetooth LE
Note: This KBA has been marked as deprecated. A more updated KBA can be found here:
Why is pairing with iOS not working?
Since iOS 9.1 update pairing without bonding is not any more supported by iOS. Calling this API command without being in bondable mode, will cause the connection to fail with devices running iOS 9.1 or newer.
Before using this API command with iOS9.1 or newer you must enable bonding mode with command Set Bondable Mode and you must also set then bonding parameter in this API command to 1 (Create bonding).