While Google seems to be already in the final stages of developing the upcoming Android N platform, some flagships have yet to receive their Android Marshmallow update. Tech manufacturers like Samsung are now hurrying up to complete their Android M roll-out.

The latest Samsung flagship devices to get the Android M treatment are last year's Galaxy S6 and S6 Edge releases. According to TechTimes, the South Korea-based tech giant has just finished its carrier-specific version for T-Mobile users and the U.S. carrier has announced that an Android M notification has started rolling out to their subscribers using the Galaxy S6 lineup.

As for the phablet variant of the lineup, the Galaxy S6 Edge+, the industry follower said that T-Mobile has listed its update version to be in the "Manufacturer Development" stage. This is the first phase in an Android firmware update, meaning that the carrier is still talking with Samsung about building an Android M version for the plus-sized flagship.

Meanwhile, it seems that T-Mobile is the last carrier to roll out a locked version of the Android M update. The update makes AT&T – which promised customers a March release for Marshmallow -- the only major carrier still in the process of finalizing an Android M version. Earlier this year, Sprint and Verizon rolled out their own Android Marshmallow updates to their Samsung Galaxy S6 lineups.

However, apart from the Galaxy S6 lienup, some carrier-specific Samsung flagships have already received Android M. Previously, global releases of older Galaxy devices like the Galaxy S5, Galaxy Note 4, and Galaxy Edge received their Marshmallow updates. According to IB Times, Sprint released an Android 6.0.1 version for the Galaxy Note 4.