Phone Number Schema with Required National Number and Optional Country Code

The country calling code (CC), in its canonical international [E.164 numbering plan format](https://www.itu.int/rec/T-REC-E.164/en). The combined length of the CC and the national number must not be greater than 15 digits. The national number consists of a national destination code (NDC) and subscriber number (SN).

The national number, in its canonical international [E.164 numbering plan format](https://www.itu.int/rec/T-REC-E.164/en). The combined length of the country calling code (CC) and the national number must not be greater than 15 digits. The national number consists of a national destination code (NDC) and subscriber number (SN).