Help: Phone number format in a cell

[Junda Ong]

*I want to enter phone number in E.164 format, that is with a prefix +, 
country code and number. For example, "+6590000000".*
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*Is it possible to format a cell to accept the number without using quotes? 
(Looks like no solution)*
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*If so, can I write a function that change the entered value and enclose it 
with quotes?*