Though T-Mobile US Inc.’s (NYSE:TMUS) June press event for its new Un-carrier services did not confirm plans for phone unlocking, the carrier is still reportedly working on software which would allow subscribers to unlock their phones for use on other mobile networks.

Last month, the unofficial insider blog TmoNews shared details of T-Mobile possibly releasing a smartphone called the Samsung Galaxy Avant, which would include preloaded software to enable phone unlocking. The device has not yet been announced, but sources for TmoNews reportedly obtained a Galaxy Avant test model and were able to unlock the device using the pre-loaded software; they got the device working with a SIM card from Verizon.

Now, the insiders have obtained an internal guide, which describes how the unlocking software for the Galaxy Avant functions. It is believed that phone unlocking on T-Mobile may be made available only for specific phones, like the Galaxy Avant.

The unlocking application is called “Device Unlock,” according to the guide. Once launched on a compatible T-Mobile smartphone, the app connects the device to a server, which will give the user options for a temporary or permanent unlock. The device then sends out the unlock request and informs the user if the request was successful. Rebooting the device completes the process.

Currently, unlocking mobile phones is illegal in the U.S., but the Senate recently passed a bill, which could potentially allow mobile phone users to unlock their devices in the U.S. without violating the Digital Millennium Copyright Act (DMCA). The bill has now gone to the House of Representatives for further consideration.

It is unlikely that T-Mobile will announce any phone unlocking service until such time that phone unlocking is once again legal, but that might not stop the Magenta network from experimenting.

TmoNews expects this unlocking feature would be exclusive to Android devices since Apple Inc. (NASDAQ:APPL) disapproves of preloaded software from third-party sellers.