While testing out the new Notifier component to write some docs about it (ref symfony/symfony-docs#13025), I've found the AdminRecipient classname a bit confusing. It makes sense when purely looking at it from an error notification perspective.

However, I think the Notifier component shines in being able to sent any kind of notification to any kind of transport.

I would propose to merge this with Recipient, so the base class can have both email or phone:

$recipient = (new Recipient())->phone(...);
$recipient = (new Recipient())->email(...);
$recipient = (new Recipient())
    ->phone(...)
    ->email(...)
;