Link passwordless SMS identity to pre-existing user


I’m looking to allow users to log in with either email and password or passwordless sms or email, but I want to get phone numbers for all users.

For users who log in with email, I want to prompt them to link their phone number. I see that I can prompt users to add a connection and specify the connection type as described in this article: User-Initiated Account Linking: Client-Side Implementation

However, it’s not clear to me how show a screen that only allows sms passwordless connections. I don’t see passwordless sms as a connection “type”.

How can I prompt existing users to link their phone numbers?