I think I am not able to make things clear for you guys, for that I apologize.
Here is what we are actually trying to implement.
1) We are using the Test account.
2) User will come to our website and can select a subscription (recurring) or a one time payment.
3) In case of subscription, the user is charged first time when he completes the checkout process and if the AIM response is positive we update our database but, at this same time we also create a ARB for the defined period of the subscription, which in this case is set to 7 days (for testing purpose). Now after this 7 days, user's card is again charged for the defined amount and we want a callback which can be used to update our local database. We understand that in this case we will receive the response similar to AIM.
Basically we are not able to receive the second callback, which is set to fire after 7 days of the first transaction.
I hope I was able to explain what we are looking for.
Thanks again for all your support.