From Wikipedia UMTS: Universal Mobile Telecommunications System (UMTS)' is a mobile standard of the third-generation (3G).
In Japan, only UMTS is available, no GSM network exists there. For this and other reasons, support for UMTS is very desirable. This can be accommodated in the device itself or externally with supported peripheral hardware via UMTS tether mode using USB, Bluetooh, WiFi or infrared. The 2nd generation of Apple's iPhone (iPhone 3G) supports now UMTS, too.
Ideas for a workaround for the Freerunner
If you have installed a distribution like debian you could get UMTS running with a simple USB-Modem and a low-cost usb gender changer. The stick should be recognised as a mass storage but with UMTSmon crosscompiled you should be able to use it as a modem. A list of supported devices is found here.
If you have still problems using the card as a modem have a look at the USB-Modeswitch within the sid/unstable tree.
If your Neo then detects the stick as a modem you could use WvDial or similiar tools to establish a connection.
Some instructions could be given by this page.