Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
It's showing that your phone is currently set up to work with a text phone device for the deaf.

A phone atop of seven small dots means that it is set to work with TTY. TTY, also known as Text Telephone Device or Telecommunication Device for the Deaf (TDD), is a special device required at both ends of the conversation that enables people who are deaf, hard of hearing, or speech-impaired to use the telephone to communicate. TTY works by allowing people to type messages back and forth to one another instead of talking and listening.
 
This is TTY symbol. Some kind of facilitation for deaf people. You can turn it off in your settings.

If you notice this symbol within the status bar, this means that TTY is on.

Teletype (TTY) machines are utilized by hard of hearing and difficult of hearing individuals to communicate by typing and reading through text. If you possess the iPhone TTY Adapter, offered at world wide web.apple.com/store, you should use iPhone having a TTY machine.
 
Settings -> Phone -> TTY. Turn it off. Unless you use TTY.

Edit - sorry for the redundancy, I was composing my message and hit send a minute after others did. :)
 
It's showing that your phone is currently set up to work with a text phone device for the deaf.

A phone atop of seven small dots means that it is set to work with TTY. TTY, also known as Text Telephone Device or Telecommunication Device for the Deaf (TDD), is a special device required at both ends of the conversation that enables people who are deaf, hard of hearing, or speech-impaired to use the telephone to communicate. TTY works by allowing people to type messages back and forth to one another instead of talking and listening.

You were first ;).
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.