Rectangular smiley

Hello
Generally, you receive this when your phone is unable to understand the SMS sent.
We did not send you a square with a cross... but a real image... a real smiley! You're the only one who sees a cross... because your phone does not understand or does not have that smiley in its knowledge base.

My advice
Don’t try to install a ton of smileys that will bring ads and other crap
Forget that square!
But I'm just saying this, I'm not saying anything, it's just my personal opinion.