http://download.cnet.com/inSSIDer/3000-18508_4-10848357.html
WHen you say unit... your in an apartment or townhouse?
Then there quite likely is alot of interfearance.
This might be a good idea to do anyways.. at min to increase speed, etc performance.
Its not to rule out.. it could be a PHONE issue still... only surefire way for that, is to do a factory reset on it.