Does calling 999 if you are kidnapped and then pressing 55 let police know that "you can't talk, so they will track you"? No, that's not true: the National Highway Traffic Safety Administration (NHTSA) told Lead Stories that it was not aware of such a service in the U.S. NHTSA's National 911 Program coordinates "federal efforts that support 911 services across the nation." In the United Kingdom, 999 is the emergency services number, the equivalent of 911 in the United States.
If you get kidnapped you can call 999 then you need to press 55 after the "you are through to the police message " and they'll know you cant talk so they will track you
This is what the post looked like on Facebook at the time of writing:
(Source: Facebook screenshot taken on Mon Jan 4 23:49:51 2021 UTC)
The author of the Facebook post is based in the United States. Even if the post had meant to say, "911" instead of "999," it wouldn't have made a difference, according to a statement NHTSA emailed Lead Stories:
No similar function exists in the United States, to our knowledge.
However, text to 911 - which many people use when they can't talk - is available in many jurisdictions. The Federal Communications Commission maintains a voluntary database of participating law enforcement agencies: https://www.fcc.gov/general/psap-text-911-readiness-and-certification-form.
Some states, such as Massachusetts, have silent call procedures that offer a caller the option of responding to dispatcher's questions by pressing "4" for yes and "5" for no. The feature isn't limited to kidnapping, and is available if for any reason a caller is unable to speak with an operator.
The UK's Silent Solution system offers 999 callers the option of pressing 55, but only when prompted, This doesn't make it possible for police to track a person. Use of this feature is not limited to kidnappings.