Ericsson T68i with HBH-60 Bluetooth Headset problem

With the HBH-60 Bluetooth Headset on incoming unanswered calls when I
press the "button on the Bluetooth headset" 10% of the calls will be;
* Hung-up, and not answered
* The call will be picked up on the phone and not the headset
The other 90% of calls will be answered normally

I did have a HBH-15 Bluetooth Headset that worked perfectly

While I do have other Bluetooth devices that can interfere, the
problems still occur when all Bluetooth and 2.4GHz devices are turned
off over a long period of time.