I am not familiar with SMS but any user account used as a service could
possibly do such. If you are a local administrator and it does not violate
any computer user policy you can add any user to the user right for deny
access this computer from the network in Local Security Policy under local
policies/user rights if that policy is not defined at the domain level.
However it may be in your best interest to voice your concerns with your
managers and support staff first with evidence in hand of access from
unathorized user.  --- Steve