In one case, a 12-year-old girl received obscene and vulgar texts. Her mother did not know where these numbers were coming from.
Mysterious, random numbers can be generated by several different apps to conceal who is texting you.
If you get a text from a strange number, you should make sure to preserve the texts and call police. You should also take screen shots of these texts and do your best to block the texts and block the number so you don't receive anything more from that person.
In addition, detectives may be able to issue a subpoena to find out who is behind those numbers.