Embedded SIM (eSIM) which is also known as soft SIM is an initiative by GSMA to develop a new SIM standard that allows re-programability and remote activation, giving customers the ability to switch carriers without getting a new SIM card.

With the eSIM, customers can choose a new carrier over the phone and get his or her service activated via Over-The-Air (OTA) provisioning. However, the eSIM is expected to be implemented in the machine-to-machine (M2M) communications first before it goes mainstream in smartphones. 

The new standard is expected to be ready sometime in 2016.