Asterisk coding needed to enable unmask of caller ID over SIP trunk with supported DID service, module is very simple:
1. Incoming call to DID
2. caller ID stripping from PAD header
3. hang up
4. initiate 2 seconds call back to predefined number with caller ID that was stripped from blocked call
5. hang up
Please bid only if you have knowledge in unmasking CID and have DID / Trunk providers to support both tasks.