Node.js Phone Number Login API

I need a login API in Node.js that authenticates users via their phone number and a default OTP.
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- The API should support user login with a phone number as the input.
- Upon successful input, the user should be authenticated using a default OTP.
- The default OTP for all new users should be a fixed code, for instance, '123456'.
- PostgreSQL Database.
To sum it up, I'm in need of a simple, secure and efficient login API that can authenticate users via their phone number and a fixed OTP.

Ideal Skills:
- Proficiency in Node.js and API development.
- Experience in user authentication systems.
- Understanding of phone number validation and OTP generation.