You might have problems with power (different power system) and a converter might be needed for that. As for the phone system, not real sure, but UIT is a international standard for commutations. If I was you I'd call 3Com/USR and ask...
I have several of these, most sitting on shelfs right now, and they are tanks.
If there is any problem, besides power requirements, it might be the recognition of dial tone. I've had people from the US go to Europe and we had to disable it with (I think) ATX1 or X0, one makes it do a blind dial, not checking for dial tone first. After that they were fine.
I do know we have had USRs dial from US to Europe and they sync and move data just fine.