Help identifying special green phone icon

[BAZSHAW]

Galaxy S02 on Verizon network. When selecting a contact to call, I'm seeing two green phone icons. One is the 'normal' one, the other has the letter T and 3 lines behind it, as in the photo uploaded.  No idea what this is, can someone enlighten me!

thanks

[BAZSHAW · Accepted solution]

OK I figured it out!  It denotes Real time Text (RTT) is enabled.  Disabled it and icon went away/