Hi Zenners,

Since I sell software for mobile applications, I need to add the following behavior to my checkout process:

1. When the customer checks out, the checkout php code needs to call my php function that generates a unique code for the purchase.
2. I need to also modify the php code to call my function that sends the user's mobile device an SMS text message with a URL and the generated code.

I'm not sure what php file or files to modify? Any pointers to help me make these modifications would be greatly appreciated.

When I find the file or files to modify, I'll copy them to a myTemplates directory (keeping the same directory structure) and modify them there so my changes will be preserved with zen_cart upgrades. Is this the correct procedure?

I also need to modify the user registration information to include the user's mobile phone carrier (as a dropdown box) and then save that carrier_id in the zen_customers table. I'm guessing that making these two types of changes (to the checkout php code to call my php functions and to modify the user registration to include the carrier) will be similar. Some pointers as to which files to modify would greatly speed up my developmernt process, and they would be greatly appreciated!

Thanks,
jdl