[This question](https://stackoverflow.com/questions/487906/java-phone-number-format-api) asking for a phone number format API in Java got me wondering why such an API doesn't seem to exist. Given the number of [validation](http://commons.apache.org/validator/apidocs/org/apache/commons/validator/routines/package-summary.html#package_description) classes available under [Apache Commons](http://commons.apache.org/), I would have thought such an API would be included.

My question is, does anyone know of a phone number formatting/validation library available in **any language** that could be used as a model for a small Java open source project? Also, other than the large number of different phone number formats used throughout the world, does anyone know of any reason that such a project would be infeasible?