Well Cartman,
if you get shot down you won't be the only one. They bang it in at the college of knowledge that the transition from mach to IAS starts about FL290/280-ish on modern airliner types.
Starboard, you don't mention if were flying on a mach first so we're all assuming you were and therefore you got the "transition" specification. It seems to be said in lots of different ways (partly the ATCO trying to keep RT down, partly trying to acknowledge that some speeds are unrealistic at various levels). I believe there was a discussion on here once upon a time about the use of the term transition (potential confusion with transition altitudes, etc.)
WW