UN M49 area codes are available via two enums that implement the area codes by either alpha-2 or alpha-3 codes from ISO 3166-1. Though UN M49 defines area codes only in numeric form, technical limitations on the naming of identifiers in .Net means that the enum members must have an alpha (or alpha-numeric) form to satisfy these requirements. This means that some area codes will only be accessible as metadata as they do not relate directly to an ISO 3166-1 country code.
To access an area code directly, you must first know the country code to which it is related. For example,
var switzerlandAreaCode = (ushort)UnM49AreaByAlpha2CountryCode.CH;
Or by its alpha-3 country code,
var switzerlandAreaCode = (ushort)UnM49AreaByAlpha3CountryCode.CHE;
Other area codes can be retrieved indirectly from a member of one of these enums using the provided extension methods that access this information from the area code’s metadata (see Access area metadata).