HI all

I am new to web services and am looking for advice on the following
We are running dontnet frame work 1.1 sp1 on windows advanced 2000.

I've been asked to look at a merthod for collecting online payments.

The plan is to get the amount of money to be payed to us and then fire
the user off to a third party broker to collect the money. After we
send the initial request we are effectivly out of the loop.
After the transaction is compete the 3rd party will send back a call
back report containing some autheticaton info, an Id for the
transaction, and an accept or decline flag.
This takes the form of a URL query string which I have to parse into
the appropriate data field

Ok here's the possible web service bit.
The 3rd party will not do any work to add a web service reference to
the payment facility,
they have requested that we supply a URL that will accept and process
the information automatically.
So on to the question:
Can a webservice be called and executed in this fashion?
If so what format would the URL take?
If I am on totally the wrong track and you have any suggestion they
would be very much appreciated.

thanks in advance

Mikey