Dear Mike,

Thank you so much for your guide, I checked http://www.authorize.net/ and as you have mentioned there are a lot more on the Net such as:
http://www.chargegateway.com/
http://www.arvicsecure.com/
http://www.ccavenue.com/content/credit_card_processing.jsp
http://www.merchantexpress.com/
http://www.paynetsystems.com/
http://www.collectivepos.com/
http://www.richsolutions.com/
and ...

If you had an idea to present a path to know what to do, I would be appreciated.

For example, there is a POS machine or a sweep card reader, then our application should be connected to the device, I think it should be come with an API, then we need a secured session layer SSL service and a service provider to process the credit cards, am I right?

...Farhad