Not sure about the Fusic, but not all Sprint phones have firmware that allows it. SMS while roaming used to not be supported by Sprint, but they seem to have changed that policy a couple of years ago. Some phones (new models) can, some can't, and Sprint is not known to issue firmware updates to support new funcationality in phones. For example Sanyo 2300 can receive SMS while roaming, but not send. Sanyo 2400 and Katana can do both.