Were you able to do this in steps, first evaluating your data -
index = my_source - did return some events,
index = my_source | regex my_source_field="(*|#)(31|67|82|65|77|87)" - did populate the field my_source_field,
then if that is the case, try adding the following
| eval feature_code = case(my_source_field like "%31%","Caller ID Blocking Per Line",my_source_field like "%67%","Caller ID Blocking Per Call") | table feature_code
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