2N BRI gateways support calling number modification.

You can find this setting in the section Configuration – List of prefixes – Tab. of replaced prefixes (see figure)

How exactly does it work?

All numbers starting with 0 are "matched" in Prefix List 1 and the digit 0 is automatically replaced by the number 00420. Then the rest of the digits after the replaced digit 0 (ie the number 7 1234 5678) are compared in the Prefix Table. If I successfully match the rest of the number here as well, the call continues to the LCR table, where the SIM card is assigned to make the call.