So many;
Are u free
Are you busy
Are you still working
Are u working
What are you doing
Where are you
Can be phone call or text or email, some using email for short notice

just baffling
Are you available
What's your availability
These last two are annoying because some are enquiring about availability today, others next week, next month but they say the same. Also I'm mostly outcall and people requiring outcalls can be anywhere from ten minutes travel to two plus hours (which I do offer), availability depends on the location but I'm given zero information.