BlackBerry Messenger
A PIN instead of a phone number, and a D for delivered.
Free messaging when texts still cost money, on a phone with a proper keyboard.
The delivered and read receipts are standard now and were revelatory then. Broadcast messages were the original group chat and were mostly chain letters.
BBM was the reason a generation of British teenagers had a BlackBerry Curve rather than an iPhone, right up until it was not.
Cost back then
Free with the data plan
Goes for now
Working BlackBerry Curves are collectable
