Add callout to clarify the restrictions around countries for phone numbers (#2840)

Co-authored-by: Michael Novotny <manovotny@gmail.com>

Author: SarahSoutoul

docs/guides/configure/auth-strategies/sign-up-sign-in-options.mdx

@@ -38,7 +38,7 @@ SMS functionality is restricted to phone numbers from countries enabled on your
 
 ### SMS allowlist
 
-SMS functionality, including SMS [OTPs](!otp), is restricted to phone numbers from countries that are enabled on your SMS allowlist. This can be useful for avoiding extraneous SMS fees from countries from which your app is not expected to attract traffic.
+SMS functionality, including SMS [OTPs](!otp), is restricted to phone numbers from countries that are enabled on your SMS allowlist. This can be useful for avoiding extraneous SMS fees from countries from which your app is not expected to attract traffic. **By default, only the US and Canada are enabled.**
 
 Every instance starts off with a default set of enabled SMS country tiers. To tailor it to your needs:
 

docs/reference/javascript/types/phone-number.mdx

@@ -8,11 +8,16 @@ The `PhoneNumber` object describes a phone number. Phone numbers can be used as
 
 Phone numbers must be **verified** to ensure that they can be assigned to their rightful owners. The `PhoneNumber` object holds all the necessary state around the verification process.
 
+The verification process consists of two steps:
+
 - The verification process always starts with the [`prepareVerification()`](#prepare-verification) method, which will send a one-time verification code via an SMS message.
 - The second and final step involves an attempt to complete the verification by calling the [`attemptVerification()`](#attempt-verification) method, passing the one-time code as a parameter.
 
 Finally, phone numbers can be used as part of [multi-factor authentication](/docs/guides/configure/auth-strategies/sign-up-sign-in-options#multi-factor-authentication). During sign in, users can opt in to an extra verification step where they will receive an SMS message with a one-time code. This code must be entered to complete the sign in process.
 
+> [!IMPORTANT]
+> SMS functionality, including SMS [OTPs](!otp), is restricted to phone numbers from countries that are enabled on your [SMS allowlist](/docs/guides/configure/auth-strategies/sign-up-sign-in-options#sms-allowlist). This can be useful for avoiding extraneous SMS fees from countries from which your app is not expected to attract traffic. **By default, only the US and Canada are enabled.**
+
 ## Properties
 
 <Properties>