Google's common Java, C++ and JavaScript library for parsing, formatting, storing and validating international phone numbers. The Java version is optimized for running on smartphones, and is used by the Android framework since 4.0 (Ice Cream Sandwich).

https://github.com/googlei18n/libphonenumber

Mapping Phone Numbers to carrier

PhoneNumber swissMobileNumber =

new PhoneNumber().setCountryCode(41).setNationalNumber(798765432L);

PhoneNumberToCarrierMapper carrierMapper = PhoneNumberToCarrierMapper.getInstance();

// Outputs "Swisscom"

System.out.println(carrierMapper.getNameForNumber(swissMobileNumber, Locale.ENGLISH));