I am using a 3410 with software version V.02.32 11-03-02 NHM and another 3410 with the version V03.06 24-04-02 NHM-2.

What are the differences between the 2 versions. We are unable to download to either handset.
Is there a newer version of the firmware that I need on the handset to download?
If so, how do I go about changing the firmware?