The Mobile Telecommunications Network Business applicable to these Regulations refers to Mobile Telecommunication Business, the Third Generation (3G) Mobile Telecommunications Business, and Mobile Broadband Business.

The Mobile Telecommunications Network Business Operators (hereinafter referred to as “Mobile Operators”) shall provide their subscribers with Number Portability with the following numbers of classification:
1. A mobile telephone number;
2. 080 free phone number.
Mobile Operators shall not restrict MVNOs to provide Number Portability of re-assignation of telecommunications numbers provided in the contract with the cooperative MVNOs, and any terms in violation of this provision shall be null and void.
The Mobile Operator, which undertakes the called Ported Subscribers Network that the MVNO belongs to, shall negotiate with the said MVNO for the proceedings provided in Article 15 and Article 21, 22, 23, 24 and 25. The proceedings, which could not be disposed by the MVNO by nature or be disposed by the Mobile Operator through mutually negotiation, shall be disposed by the said Mobile Operator within scope of the above proceedings.
The MVNO of the Ported Subscribers shall provide the necessary data of the Ported Subscribers upon the Mobile Operator’s request when it implements the proceedings as referred to in the preceding paragraph.

Mobile Operators shall provide Number Portability for their subscribers upon the date of obtaining allocated telephone numbers.

(Deleted)

When a Ported Subscriber ceases to use his/her existing telephone number, the Recipient Operator shall return that telephone number to the original Mobile Operator assigned it within seven days either thereof or after an announcement service, if any, is terminated, and shall perform the required notifications in accordance with the provisions set forth in Item 10, Paragraph 1 or Paragraph 5 of Article 22. As the original service provider assigned that telephone number has stopped its business operation or that telephone number is not held by any Operator, that telephone number shall be returned to the NCC.
The term “cease to use” as referred to in the preceding paragraph does not include the conditions that an inheritor continues to use a telephone number through inheritance, or a surviving or new company continues to use its forerunner's telephone number after consolidation or merger, or number Ported Subscribers under service contract to the Recipient Operator apply for the other user continue to use the original telephone number.
Unless a Ported Subscriber ceases to use his/her existing telephone number, the Donor Operator shall not reassign that telephone number to another Subscriber.

Mobile Operators shall mutually provide Number Portability on a reciprocal basis, and shall conform in accordance with the principle of impartiality and reasonableness, and shall be non-discriminatory.

The service contract between a Fixed Network Operator and its Subscribers shall, in a distinct way, state the following proceedings:
1. Subscriber may request for the provision of Number Portability from the implementation date of provision of Network Portability service.
2. Mobile Operators may offer a Subscriber's data necessary for the provision of Number Portability to other Operators, Type II Telecommunications Operators, and the Administrator of Concentrated Databases.
3. Mobile Operators may charge fees for porting process of Number Portability in accordance with Paragraph 1 of Article 43.
4. The operational procedure of the remaining sum of pre-paid card when Mobile Operators provide Number Portability to the pre-paid card subscribers.
If the service contract between a Mobile Operator and its original Subscribers has not contained the provisions set forth in the preceding paragraph, the Mobile Operators shall inform its original Subscribers by written form within one month from the implementation date of Number Portability.

Mobile Network Operator shall maintain reasonable quality of customer services and quality of network performance, when providing communications services for Ported Subscribers. By January 10 and July 10 of each year, each Mobile Operator shall compile and submit information on the number of Subscribers ported to/from its networks, the failure rate of porting process, average duration of porting process, additional call set-up delay time on average calculated by calling sampled Ported Subscribers, and so on, for the previous six months to the NCC. The report formats shall be formulated and announced by the NCC.