A ported number may still match its original allocation even when the present network differs.
Keep the number
In supported jurisdictions, customers can retain a number when switching provider under applicable rules.
Separate two dates
The allocation record describes where a range began; a routing database may describe where it now terminates.
Interpret with restraint
Country and range may remain useful, but current-carrier and subscriber claims need current authorized data.
What moves, what stays
Portability separates the number someone keeps from the provider serving it. The example below is a conceptual explanation, not a port request.
Telephone number
Before: Same number
After a hypothetical port: Same number
Original allocation record
Before: Provider A
After a hypothetical port: Still describes the original allocation
Serving provider
Before: Provider A
After a hypothetical port: Provider B
Static prefix lookup
Before: May return A
After a hypothetical port: May still return A
Portability availability and procedures depend on the relevant country and service. A number-only prefix table cannot establish that a particular number was ported.