Starting from late October 2017 the Indonesian government - through a regulation from Indonesia's Communication and Information Ministry (and supported by the nation's cellular service operators) - ordered all sim card holders of prepaid mobile phone subscribers to re-register their cards in an effort to clean up the data bank and combat misuse of SIM cards, while protecting registered SIM card holders by preventing their phone numbers being misused.

Over the past decade or so many Indonesians had bought SIM cards using fake names and without any valid KTP or KK data. In most cases this was innocent as the buyers simply wanted to take advantage of a new and temporary discount or promotional package (fake names have to be used as there is an official limit of three SIM cards per Indonesian citizen). However, the lack of clear data also allows room to criminal activities (including terrorism).

This government re-registration program is a gradual one. In the first phase (1-31 March 2018) the Indonesian government blocked all incoming calls and SMS messages of those SIM cards that were not re-registered. This first phase has already ended and resulted in 100.9 million SIM cards having been blocked.

In the second phase (1-30 April 2018) the government will block outgoing calls and text messages of those SIM cards that have not been re-registered. Lastly, after 1 May 2018, prepaid SIM cards that have not been re-registered will be fully blocked.

For Indonesian nationals it was fairly simple to re-register, namely by sending a text message with a specific formula: for example ULANG#(KTP number)#(KK number)# to 4444 was sufficient those who use a XL Axiata number. Many foreigners who live in Indonesia, however, complained that such text messages failed even though they could replace the KTP and KK number with their passport, temporary stay permit (KITAS) or permanent stay permit (KITAP) numbers. For example, one foreigner tried to send his KTP number in combination with the KK of his wife (after marriage the foreigner was added to this KK). But it failed. The solution was to simply pay a visit to the branch of your mobile telecommunications services operator and bring your passport.

Blocked SIM cards 01-31 March 2018:

Operator Blocked SIM
Tri  26,661,849
Indosat  17,531,243
XL  11,232,147
Smartfren   2,149,174
Total 100,888,385

Source: Bisnis Indonesia