tracking number handy … g_ups.html

please explain:
tracking number handy?

A tracking number is a consignment (parcel reference) number.
handy - derives from ‘to hand’ = ready

Have your parcel reference number ready.

can I also say: tracking number = identity number?
but I haven’t found anywhere that ‘handy’ can mean ‘ready’,

The usual term for consignments is ‘tracking number’… the number that will allow the parcel to be tracked while it is in transit.

definition 2: located or stored in a convenient place… in other words, ready to be used. ‘ready’
oxfordadvancedlearnersdictio … nary/handy