the bandswitchtool allows a user to switch his Wallaby between the following operating modes:
900 Mhz
1900 Mhz ( USA / sx56 mode )
900 + 1800 Mhz ( normal european mode )
this functionality is also present in the bootloader, BandSwitchTool provides a more userfriendly tool.
in AT&T roms a similar tool is included in the control panel. BandSwitchTool was written to allow AT&T users to use the SpecialEditionROM, and still retain the possibility to switch bands.
On the Himalaya there is no more need for this tool, since it is a three-band phone.
here