You can use omni-channel templates to send FriendTalk or ConsultationTalk messages on the KakaoTalk channel of the Conversation API. In either scenario, the template being used does not need to be approved by KakaoTalk.
Note: Approved templates are only required when sending AlimTalk messages.
You can create omni-channel templates using the Conversation API's Message Composer or using the Template Management API.
You can learn more about working with templates on the Sinch Developer Documentation site. There, you'll find comprehensive documentation that illustrates how Sinch supports KakaoTalk through the Conversation API.