You can teach an old mobile new tricks

I have been using my Motorola C350 (or is it C35? I can never quite remember) for more than three years, and never knew that it had this feature: if you are exchanging a lot of SMS messages with someone, there is some point at which it realises that what is happening is actually a chat, and changes to chat mode, with an interface that is functionally identical to an IM chat screen. Neat.