TODO: Add number unique representation.

[IceMikl]

• Decide, how to handle phone numbers, how they will be represented.
• Create a class, which will save information about the phone numbers. -> PhoneNumber class must have a unique representation.

[IceMikl]

Phone number format:

• plus : boolean (e.g. true or false)
• countryCode : str (e.g. 0 in 44)
• nationalDestinationCode : str (e.g. 7911)
• phoneNumber : str (e.g. 123456)
• stringRepresentationFull; str (e.g. +447911123456)
• stringRepresentationLocal: str (e.g. 07911123456)

[IceMikl]

Good sources: https://support.twilio.com/hc/en-us/articles/223183008-Formatting-International-Phone-Numbers.