Have you read the description???
i think you should read the description of the Jabra carefully.
They write, that you have to put the bluetooth-device on the side of your body, where you put the Jabra on your ear."Because the human body can make interferences."
Second, i think you have paired your device with the jabra in front of you. Don't do that. When the devices will pair, they changes some parameters of frequences. So do that:
Put your headset on your ear, search for devices on the pda, and after you put the code in, put the pda on the position where you will wear it.
After 30sec. look if it is OK! Than test, if it is crackly.
When it is not OK, delete the pairing devices, Reset both of them, go to another place (2m away, because of interferences) and try it again.
So, in the worst case, after 3 times, i have no crackly!
Good luck, Mario