An interesting but probably not well known functionality of the SMS system are delivery reports. By default, requesting delivery reports is usually deactivated in the mobile device, so few people know about it. On Symbian phones, delivery reports can be activated in the SMS settings. Once active, the SMS Service Center sends a report back to the originator as soon as an SMS has been delivered, which is then displayed for a couple of seconds on the screen and also put into the "Delivery Reports" folder in the SMS application. So while this feature works well for SMS messages to other subscribers of the home network, I was wondering if it also worked when sending messages to other networks, both national and international?
The quick answer is yes. I tested this by sending an SMS to a SIM card of another national network operator and to SIM cards from network operators in Italy, Spain, and for the ultimate test, Thailand. To ensure the delivery report is not only sent in some cases once the SMS is received at the service center I only switched on the phone with the respective SIM a couple of minutes after the SMS was sent. In all cases the delivery report came in right after the SMS was delivered, i.e. right after the phone was switched-on and the SMS was delivered.
So in other words, SMS delivery notifications work even for international SMS transfers.