Web Service within ASP.net application

[c_shah]

I have a web application developed in ASP.net 2.0. I have to use
SQL
server authentication (Our outside hosting company only allows sql
authentication)

Inside that web application I have a web service referenced that is
actually hosted within our company.
When you use that web service within your ASP.net web application.
What account is used by that web service? (anonymous account use by
ASP.net web application? Can that web service use a different account?)