SoftSIMs implement eSIM functionality in software and so presents a very low cost solution. This approach is very popular in Asia where it is considered essential to have a very low Bill of Materials ( BoM ). The implementation of a SoftSIM eSIM solution is proprietary as no standards bodies have got involved with this method yet.

The software that facilitates a profile download can execute in one of 3 ways:

  1.  On the GSM modem processor ( e.g. the Qualcomm or MTK chip ) but does not use a silicon trust zone and so does not offer a very high level of security. The manufacturers of the GSM modem chips have released demonstration code that can be used for this.
  2.  On the processor of the OEM device itself. Most of the large Chinese handset manufacturers ( such as Xiaomi and Huawei ) offer this kind of solution and refer to it as a ‘virtual SIM’ or ‘virtual roaming’ solution.
  3.  In an STK applet on the SIM processor chip inside a conventional SIM Java-card. This is usually implemented by sending a message via USSD to a server requesting a profile download and then sending the IMSI/Ki pair via an encrypted SMS