re = /(49)\(?([0-9]{3})[\)\s\/]?([0-9]{8})/m
str = '+4917112345678
004917112345678
+49171/12345678
0049171 12345678
004312345678'
subst = '\\1\\2\\3'
result = str.gsub(re, subst)
# Print the result of the substitution
puts result
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html