For information on blocking inbound callers by caller ID on MGCP gateways via CUCM, see my old post here: http://webmaxtor.blogspot.com/2017/12/blocking-calls-based-on-calling-party-id.html
Since a co-worker and an old client just recently asked about doing it at the gateway level using SIP trunks, here's a quick synopsis of one way to do it:
Create a voice translation rule that identifies calls with a very specific number. Here for example I am focusing on the telephone number +1(716)555-1212.
!voice translation-rule 99
rule 1 reject /7165551212/
!
!


