SOS/Ecall button mystery

[Sybaris]

What year did Lexus put the SOS button in?   I understand that it became a requirement in 2018 but I have seen Gen 4s dated in to 2020 and even 2021 without this.  Can it be retro fitted if its not there?

[Herbie]

It's only USA market as far as I know. May be others but definitely not UK.

[John Hutton]

My 2019 UX has the SOS system fitted. It was one of the early cars delivered to customers so presume that all UXs have it

John

[ColinBarber]

11 hours ago, Sybaris said:

I understand that it became a requirement in 2018 but I have seen Gen 4s dated in to 2020 and even 2021 without this.  Can it be retro fitted if its not there?

It is a requirement for all new models (that have to go through (re)certification). The UX came out after and so all have that feature. 
 

Not sure if there is a time limit for all existing models to incorporate it, but the new RX would require it to be a standard feature as it would have gone through a recertification.