Bulk SMS in South Korea does not support alphanumeric sender IDs: international A2P arrives from a numeric sender marked as sent from abroad, while domestic bulk SMS needs a pre-registered caller number and a certified sending company. Advertising SMS must start with "(광고)" and offer a free opt-out. VoIP in South Korea is regulated by MSIT, and the law requires carriers to block manipulated caller numbers.
Rules last checked: October 2026.
Bulk SMS in South Korea: sender rules
| Sender type | Status in South Korea as of 2026 |
|---|---|
| Alphanumeric | Not supported by Korean operators |
| International numeric sender | Delivered with a 009 or 006 prefix and labelled as sent from abroad ([국제발신]) |
| Korean number via a domestic SMS company | Supported; the caller number must be pre-registered, and messages carry a [Web발신] label |
| Short code | Not available for international senders |
Korea has run a caller number pre-registration system for bulk SMS since 2015: domestic SMS companies may only send from numbers the customer has proven it owns. Bulk SMS resellers must also hold a sending qualification certificate, which became a legal obligation through a 2025 amendment to the Telecommunications Business Act. Since April 2026 SMS companies face stricter registration requirements, including identification codes in messages and pre-blocking systems. Expect KYC on your business and your numbers. See sender ID registration by country.
Advertising SMS rules: (광고), opt-out and night hours
The Information and Communications Network Act sets the rules for advertising messages:
- the message must start with "(광고)", meaning advertisement;
- it must show the sender's name and contact details;
- it must include a free way to refuse further messages, such as a toll-free 080 number;
- prior consent is required, and sending between 21:00 and 08:00 needs separate consent.
Adult and gambling content is prohibited. Transactional messages (OTP, delivery notices) do not need the (광고) label. See transactional vs promotional SMS and SMS opt-in and opt-out compliance.
Korean networks and message format
The three networks are SK Telecom, KT and LG U+, with MVNOs on top. Mobile numbers start with 010. Korean operators only support characters in the EUC-KR set, so test emoji and special symbols before sending. Long international messages are not joined on the handset: each part arrives as a separate SMS (about 70 Korean characters each), so keep OTP short. See OTP SMS best practices.
VoIP in South Korea: regulator and numbering
VoIP is legal in South Korea for licensed or registered providers. The Ministry of Science and ICT (MSIT) handles telecom licensing and numbering, while the communications commission handles user protection, including spam. Numbering as of 2026:
- geographic numbers start with an area code (02 Seoul, 051 Busan);
- mobile numbers start with 010;
- 070 numbers are internet phone (VoIP) numbers;
- 080 is freephone.
Korean numbers are only assigned to users with a demonstrable local presence, which limits foreign access to local CLI. See local CLI explained.
CLI rules and anti-spoofing in South Korea
Since a 2015 amendment, the Telecommunications Business Act requires carriers to secure their systems against caller number manipulation and to block numbers they find being used to mislead, and MSIT can order operators to stop serving numbers used for fraud. Korean police have prosecuted schemes that rewrote 070 VoIP numbers to look like Seoul 02 numbers on calls from abroad. For buyers, this means the CLI must be a number you hold, and calls from abroad should not present Korean numbers. See CLI spoofing rules and CLI vs non-CLI routes.
What buyers ask for on Korean routes
- Rates for fixed, mobile and 070, plus ASR and PDD.
- Which CLI the route passes and how calls from abroad are presented.
- For SMS: international vs domestic delivery, sender number registration and OTP latency on SKT, KT and LG U+.
Check coverage on the South Korea VoIP destination page and the South Korea SMS destination page, or read about our VoIP termination and A2P SMS routes. VoIPMatcher sources the route from its carriers and manages it; buyers and sellers never see each other. Request a South Korea voice route or request a South Korea SMS route.
Frequently asked questions
Can I send SMS to South Korea with my brand name as sender?
No. Korean operators do not support alphanumeric sender IDs. International A2P messages arrive from a numeric sender with a 009 or 006 prefix and a label showing they were sent from abroad. Put your brand name at the start of the message text so recipients know who is writing.
Why does my SMS to Korea show [국제발신] or [Web발신]?
Korean operators add these labels automatically. [국제발신] marks a message sent from abroad, and [Web발신] marks a message sent through an internet-based bulk SMS service in Korea. They help users spot bulk traffic and cannot be removed by the sender.
What time can I send marketing SMS in South Korea?
Advertising SMS sent between 21:00 and 08:00 Korean time needs separate prior consent on top of the normal marketing consent, so most senders keep campaigns to daytime. OTP codes and service notices are not advertising and can be sent at any time.
What is a 070 number in Korea?
A 070 number is a Korean internet phone (VoIP) number. Businesses and VoIP services use them, and they are priced separately from fixed and mobile numbers on wholesale rate decks. Like other Korean numbers, they are only assigned to users with a local presence.
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