I want access to the device’s phone number for verification in PWAs

I build Progressive Web Apps (PWAs) that use mobile phone numbers as usernames. Currently, there is no way for a web app to verify that the phone number a user has entered matches a number associated with their device — something that native apps can do via platform telephony APIs.

I want a browser-provided Telephony API (or an extension of existing APIs like WebOTP) that would allow web apps to:

1. Query whether a given phone number matches a SIM card or registered number on the user's device.
2. Verify the signed-in user's phone number against the device's phone number — with explicit user consent.

This would improve the authentication flow for PWAs, reducing friction and SMS verification costs, while keeping the user in control via a permission prompt. Similar capabilities are available in Android via the TelephonyManager API and there is prior art in the WebOTP API for SMS-based verification on the web.