You cannot stop the call arriving at your OBi110, but there are two options for dealing with it when it does arrive. Assuming that the nuisance CallerID is 01234567891:
Physical Interfaces > LINE Port > InboundCallRoute:
{01234567891:},{ph}
If 01234567891 calls, then he will receive ringing tone, but any phone connected to the OBi will not ring. This will mean your PSTN line will be "busy" until he hangs up. All other calls will ring the phone.
A more fun idea is to send your nuisance call to some free announcement, which may confuse the caller and perhaps think he is dialling the wrong number:
Physical Interfaces > LINE Port > InboundCallRoute:
{01234567891:sp1(wbdemo@conf.zipdx.com)},{ph}
That is a particularly boring message, so he should hang up quite quickly! All other calls will ring the phone.
If you need to block more than one number you need to use a digit map with parentheses like so:
Physical Interfaces > LINE Port > InboundCallRoute:
{(01234567891|02345678922|03456789333):sp1(wbdemo@conf.zipdx.com)},{ph}
