Appointment calendar problems
I've built a CRM for an international company. We have users in every timezone. There's a field for next appointment day and time. Each user in each part of the world will see these appointment times as GMT now. What I'd like to do is detect the users time zone and run a conversion so that when a user says Nov 10, 2012 at 10AM the time is automatically converted to GMT then stored in the appointment field. I've found several slick Java appointment date and time widgets that will crate a pop up calendar and time to populate the field with data in the standard mySql date format, but I haven't been able how to use PHP date functions to read the local machine timezone, convert the data entered into the field, then calculate the diference and update the hours value to GMT.
If anyone has any ideas I'd appreciate it. Once the value is GMT I have no problem converting it back to local time for display in the CRM.
If you have any better ideas let me know.
Thanks.

