If you scroll down the page in fender's link you will find in the comments section the following :-
//Someone says
April 12, 2015 at 8:18 am
Two arrows. One on top of the other, an arrow pointing to the left on the top and an arrow pointing to the right on the bottom.
Reply
simon says
April 12, 2015 at 1:46 pm
In some regions, it is probably VoLTE (voice over LTE). If you disable mobile data, after a while, it should disappear.
You should use voLTE if available as it provides better voice quality and faster connection.\\
Hans.