First trip to Seoul. Most eSIMs I'm seeing are data only, but my clinic's coordinator said they sometimes call patients the day before surgery and on follow-up days. Do I need a Korean number for that, or does everyone just use KakaoTalk/WhatsApp?
Data-only eSIM covers 90% of it. Almost every clinic coordinator will message you on KakaoTalk or WhatsApp. If you want a real number, some SIM/eSIM plans for tourists include a local number for calls + texts, they cost a bit more but it's handy for taxis and delivery apps that send SMS codes.
Ask the clinic directly how they contact patients after hours. Some have an emergency line you'd need to call from a normal number.