How Do Time Zones Work For Shabbat?

Responsa Radio #93

I live in Australia and I have a Zoom call with someone in the UK. The call is scheduled at 9:00 PM for me and 12:00 PM for them - it is therefore not Shabbat for me but *is* Shabbat for them. Do I have to reschedule this Zoom call? Am I allowed to be involved with someone else doing violating Shabbat when I'm not doing anything wrong at all?