SELECT result1 ORIGINAL_PHONE,
    regexp_replace(
        regexp_replace(result1,'[^[:digit:]+]',''), -- Remove non-digit and special phone characters
        '^(00[[:digit:]]{2}|\+[[:digit:]]{2})([[:alnum:]]*)([[:alnum:]]{3})$', -- Phone pattern
        '\1*\3') MASK_PHONE -- Mask
FROM ( 
    WITH test AS
     (SELECT '0034910000000,+34910000000' col1 FROM dual) 
    SELECT regexp_substr(col1, '[^,]+', 1, rownum) result1 
      FROM test 
    CONNECT BY LEVEL <= regexp_count(col1, ',') + 1);