SendText() — Sends text to the channel
Sends text on a channel, if
      text transport is supported. Upon completion, a channel variable named
      SENDTEXTSTATUS will be set to one of
      the following values:
SUCCESS
            The transmission of the text was successful.
FAILURE
            The transmission of the text failed.
NOSUPPORT
            The underlying channel does not support the transmission of text.
If the options parameter is set to
      j and the channel does not support
      text transport, and there exists a priority n+101 (where n is the current priority), execution will
      continue at that step.
          exten => 123,1,SendText(Welcome to Asterisk)