re = /^((\+?\d{1,4})?[-.\s]?\(?(\d{1,3})?\)?[-.\s]?(\d{1,4})[-.\s]?(\d{1,4})[-.\s]?(\d{1,9}))/m
str = '+49 172 7470791
+49 621 60-6641516
+49 621 60-41516
8-1-6641516
+7(927)296-96-08
61 41516
6641516
41516
'
subst = '$2$3$4$5$6'
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