 readmeint about the international phone number format these rules have been formulated off of the e123 for display and e164 for input specifications published by the itu in order to prevent ambiguity we have chosen to restrict some of the stipulations these specifications give in summary country calling codes are assigned by the itu telecommunication standardization sector in e164 we take an international phone number to have the form xx yyyyyyy where xx is the country code and yyyyyyy to be the subscriber s number possibly with intervening spaces the maximum length for these phone numbers is 15 reference materials can be found here http wwwituint rec trece123 en http wwwituint rec trece164 en modifications to e123 71 the international prefix symbol must prefix international phone numbers all numbers missing this symbol will be assumed to be in the default country code when reformatting numbers to a standard format the following conventions will be taken 72 parentheses will be normalized to spaces we do not support the multiple phone numbers as described by 74 users can always specify that multiple values are allowed if this is desired the functionality specified by 75 76 and 8 is not implemented 92 specifies that spacing shall occur between the country code the trunk code and the subscriber number as trunk codes are omitted by convention this means the only guaranteed separation will be between the country code and subscriber number our implementation may treat hyphens spaces and parentheses as advisory indicators as to where spaces should be placed however 1 7329060489 will stay as it was specified while 1 732 9060489 will be normalized to 1 732 906 0489 as a future feature rules may be implemented for country codes specifying these conventions however i have deemed such functionality out of scope for now the drupal task specifies that we should validate country codes however due to the highly volatile nature of these codes the author does not believe that it is a good idea to maintain a list of valid country codes thus we only validate that the country code is three or less digits modifications to e164 our processing for ndd s will be similarly constrained as per 732 we will treat 0 as a valid trunk code for all countries other digits may be specified if the fall in the form of x where x is a single digit that is 7 or 8 postscript modifications to our implementation will occur as necessary by user bug reports  