Support Free Shortcode for TracFone Customer Service

TracFone informed that the short code "611611" is owned by TracFone and this is for the free messages for the TracFone customers.

TracFone webpage for 611611 use cases: https://dsweb.tracfone.com/611611/help/



BUG: 198667013
Test: ShortCodes are tested in the USA by leesung@google.com.

Change-Id: I6addc2c6a25e774cf9ba905b837e15caaed3c9bc
Signed-off-by: Shawn (Yu-Hsiang) Lien‬ <shawnlien@google.com>