[AccessD] Credit card processing

Dear List:
I am looking for suggestions/products for adding credit card processing
to an existing AXP order-processing application with about 10 users.
Right now, the users get the credit card info over the phone and go to a
credit card swiping machine to key in the info - what the client wants
is to have a button on a form to do that.  They get about 10-15 orders a
day and typically ship the same or next day.  In my own investigations
I've learned something of the distinction between gateways and
processors, and it appears that the latter would be sufficent for this
application, but if using a gateway is a better approach I'd like to
know that.

Thanks in advance, 

Phil Jewett