Creating a phonebook for employees

I am currently planning to create a simple phonebook on Erpnext.

Basically it will give employee names, internal no and mobile no only. I have customised Erpnext with ease thanks to developer.

Which way should I take? I am planning to create a section under HR and find a way to list names and related numbers there. Or, use codes from similar module then use it as phonebook?

What I would do is use the Employee file and create a custom report for it using the report builder. You can select to show just that information, and you won’t have to go through the trouble of creating new doctypes.