While eSIM adoption has been growing steadily, physical SIM cards are long from gone just yet. Remote provisioning is the key strength of the eSIM architecture, which means the embedded SIM can be easily programmed by installing the desired carrier profile. Programming a physical SIM card, however, is a difficult job. For example, if you've got a SIM that shows the "Unknown" value under the Phone number on SIM property in the Android system settings, there's no easy way to change it.

Phone number on SIM Unknown

As usual, XDA's modding community has come to the rescue. Kieron Quinn, AKA XDA Recognized Developer Quinny899, has published a handy Xposed module that can populate the "subscriber number" field on the SIM card. SIM Number Setter is an aptly named app that invokes Android system-level codes, which are otherwise unused to write the phone number (the MSISDN for a GSM phone, to be precise) to the SIM in a permanent way. This is particularly useful after porting a number to a different SIM, or simply replacing the factory-defined "Unknown" tag for the SIM as seen on apps such as Google Messages for the sake of tidiness.

SIM Number Setter Xposed module

To set a new "subscriber number," you can enter anything in the field, as long as there are 20 or fewer numeric characters or the plus ('+') sign. Due to the fact that the number gets written into the SIM card's memory, the change will survive without the existence of the Xposed module. As the developer described:

If you don't have a rooted device, or don't want to root your main device, you may wish to consider rooting an old device, and temporarily putting your SIM into that device, using this app, and then putting it back in your main device - the fixed number will travel with it

Keep in mind that the module can't change any other identifiers on the SIM chip. It is neither possible to alter the actual phone number, nor tinker with the subscription parameters associated with the number. Moreover, SIM Number Setter will not help you to unlock a network-blocked SIM.

If you are interested in playing with the SIM number, check out the app thread below. SIM Number Setter is open source, and the source code of this module is available on the developer’s GitHub profile.

SIM Number Setter: Download ||| XDA Discussion Thread