re = /^[-()+ .]?(?:[0-9]+[-()+ .]+)+[0-9]+$/m
str = '9999 999 999
+91 99 99 99 9999
999.999.999
99999999
677887 78787
99 (999) 99 99
9999 999 999
+91 99 99 99 9999
999.999.999'
subst = ''
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