If each person is assumed to be a Singaporean-based contact then phone numbers should be designed to only accept Singaporean-based phone numbers.
However, then if it is not a Singaporean-based phone number and is longer than 8 digits I would need some form of method to indicate the extension code. such as +102 [number]. Thus, overall if the assumption is Singaporean contacts phone number should be designed to only accept Singaporean phone numbers or be open to global contact numbers with extension support.
Non-Singaporean phone number starting digits and more than 8 digits.
If each person is assumed to be a Singaporean-based contact then phone numbers should be designed to only accept Singaporean-based phone numbers.
However, then if it is not a Singaporean-based phone number and is longer than 8 digits I would need some form of method to indicate the extension code. such as +102 [number]. Thus, overall if the assumption is Singaporean contacts phone number should be designed to only accept Singaporean phone numbers or be open to global contact numbers with extension support.
Non-Singaporean phone number starting digits and more than 8 digits.