格安SIM refers to mobile phone plans offered by MVNOs (Mobile Virtual Network Operators) that use the networks of Japan's three major carriers (ドコモ, au, ソフトバンク) at lower prices.
BACKGROUND:
Japan's major carriers historically charged high monthly fees. Starting around 2015, 格安SIM became a mainstream alternative. Popular MVNOs include 楽天モバイル, UQモバイル, ワイモバイル, IIJmio, and others.
COMMON COLLOCATIONS:
- 格安SIMに乗り換える: to switch to a budget SIM\n- 格安SIMを契約する: to sign up for a budget SIM
- 格安スマホ: a budget smartphone (often bundled)
PRONUNCIATION:
SIM is pronounced シム in Japanese, borrowing the English abbreviation. The full term is read as かくやすシム.
PRACTICAL NOTE:
For foreigners in Japan, 格安SIM is often the most accessible option, as some MVNOs have simpler contract requirements than the major carriers. Many convenience stores and electronics shops sell prepaid 格安SIM cards for tourists.