SMS for Post shipment statuses

HI,

We are trying to build a SMS functionality for customer orders that will keep the customers informed about where their goods are currently until the goods reach the customer. I wanted to know general thoughts from people who might have implemented this feature for their clients/organizations.

I basically want to know how was this feature implemented: which system was receiving events from carriers, were those events getting stored any where, was SAP (or whichever ERP) doing the job of receiving event information, what was the overall delay in sending the SMS?

We are at the stage of architecting a solution for this and wanted to know how others might have handled this.

PS: This may not be a SAP SD question per se but since SAP consultants might have worked on such functionalities, I posted this question here.