Inbound routes - addition of WITHELD as an option on CLI Number to test for.

Here in the UK when somebody calls you they have the option (either permanently or on an individual call basis) to withold their number. This is passed through to your phone with a CLI set to 'WITHELD.'

I'd like to be able to create an inbound route that sends all WITHELD calls to a recorded message stating that they must re-dial without witholding or by using their telco prefix to un-withold their number (i.e putting 1470 in front if dialling via BT).

Preferably I'd like to be able to set the CLI to anything as telco's do change the messages they send through from time to time.