We have a several 5330, and 5340 IP phones with the Wireless Dect headset and handset. I was looking into finding if the battery was replaceable on both items. The headset looks like a GN netcom headset but the handset battery was not field replaceble. Does anyone know if there is such a part and if so what is the Mitel part number. I have called both product support and sales support and no one seems to know. I find it hard to believe that no one has ever asked this question before.