Do not ever do business with InternetSecure. Ever.
I've been trying to get a stupid site linked up with them for weeks. ABSOLUTELY INFURIATING!
I've linked up sites with Authorize.net, YourPay/LinkPoint, and a number of other gateways, using a number of languages, and so on and so forth. InternetSecure advertises itself as being a drop-in replacement for Authorize.net. All I can say is that is COMPLETE B.S.!
It is _not_ a drop-in replacement for Authorize.net. For example, I was using ActiveMerchant in Ruby-on-Rails. Well, ActiveMerchant makes use of the 'encap' parameter for authorize.net. But guess what, InternetSecure ignores it! Also, the code I was using simply transmitted card information. This is fine for every gateway I've ever used. But guess what - InternetSecure doesn't support that! Again, it is NOT IN ANY WAY a drop-in replacement for authorize.net.
Then they have developers jump through hoops to get certified on their system. Just a horrendous group to do business with.
Again, despite what they tell you, it is NOT a drop-in replacement for authorize.net.