@robintrson_14069 - Billing key Error NOT_SUPPORTED_METHOD

I am currently testing Toss Payment using the billing key add card method. After going through the steps of adding card information and the verification phone number, I encountered the following error: "인증만 지원하는 상점이 아닙니다."

In the past, when testing, there was no step for verification via phone number, and I could add test card information normally. However, today I noticed that the interface has added a step requiring verification via OTP.

Could you please support me with what I need to register next?