I could have sworn it was the other way around, and this is why.
In my 2017 Mondeo I could use voice commands for several things, one of which was placing a phone call. The syntax was, call <name> on <phone type>. If that person happened to have only one phone number in my address book, then the second part was optional. So, for instance, I could have said, "call Mary at home", or "call Mary on mobile", or just plain "call Mary" if there was just one number and no opportunity for a confusion.
This was a Euro-spec car, and consequently the voice commands and navigation instructions used British English.
I would say, "call Mary on mobile", and the system would reply, "calling Mary on mobile".
One day I decided to install a software update, but I inadvertently downloaded and used a US package. I didn't realize my mistake until I tried to use the voice commands and couldn't. I would say, "call Mary on mobile", and the system would reply, "sorry, I didn't get that". But when I skipped the second part of the command and just said, "call Mary", the system responded, "calling Mary on cell". From that point on I used the syntagm "on cell" instead of "on mobile" and everything worked fine. That is, until I managed to lay my hands on a Euro-spec update package and went back to normal.