What's the Symbol near battery?

Hi.
Mate pressed something in pocket, and here's the symbol neat battery. What does it mean?
Attachment 297963

P.S. phone is really slow and very unresponssive

I believe that one's Teletype and can be found in the Accessibility section of settings.

Posted with Z10 (STL100-1 | 10.3.0.1052)

yes, looks like this.

thanks!