GPO-57 - Land line validation

[andy-preston]

Loads of “01” numbers are still not validated:

First two just need a special use-case in the validater
01#1 ### #### 11 digits
011# ### #### 11 digits
But these second two are a complete (expletive deleted)
No clue is given how to know if it should be 10 or 11 digits
01### ###### 11
01### ##### 10

It’s probably long past time that we revisited the validation anyway (it’s been a few years and things could well have changed)

https://en.wikipedia.org/wiki/Telephone_numbers_in_the_United_Kingdom
https://www.ofcom.org.uk/__data/assets/pdf_file/0013/102613/national-numbering-plan.pdf
https://stackoverflow.com/questions/44197252/how-to-check-if-phone-number-is-valid-in-android
https://mvnrepository.com/artifact/com.googlecode.libphonenumber/libphonenumber
https://stackoverflow.com/questions/31518377/is-it-good-to-use-google-libphonenumber-library-for-commercial-purpose