US Mobile has launched beta testing of a new plan feature to allow for multi-network use unlimited plans. US Mobile's flagship unlimited plan costs $50/month for a single line and includes 100GB of data at up to 5G data speeds before throttling to 1Mbps and allows 50GB of hotspot usage. Currently, customers who sign up for the plan can use it on their choice of either the Warp 5G (Verizon) or GSM (T-Mobile) network. The new plan feature will allow customers with dual SIM-capable devices to add an additional SIM to their plan either by eSIM or a physical SIM for $15/month, however, at least one SIM has to be an eSIM. Subscribers with this configuration will still only be able to use 100GB of data at up to 5G data speeds, but data usage can come from either network, depending on which network is available to use in a given location. This feature is being offered as a closed beta, and customers interested in trying it out have to leave a comment on a Reddit thread started by US Mobile's founder, Ahmed Khattak.
According to Khattak, network switching will automatically take place at the OS level (not stated by him but implied from his post) by using a phone's radio to estimate network link capacity and data usage. This will then be used to calculate a congestion ratio over a defined time window. A moving average of this congestion ratio for each network will also be stored in the user's device. In theory, phones should automatically switch to which network is performing best in a given location. Khattak seems to indicate that's how it works through internal testing. However, many iPhone users (1, 2, 3, 4) who already use similar custom setups with other networks, report that their devices will only switch to a different SIM when their phone has absolutely no signal with their current SIM. Several Android users have said the same thing. (5, 6).
What US Mobile is attempting to do with network switching is in contrast to what Google Fi used to do and Boost Infinite is attempting, allowing multiple networks with seamless network switching on one SIM. Google Fi used to offer seamless switching as well as allow its subscribers to manually switch networks as needed. Interestingly, Khattak previously trashed this idea of network switching on Reddit stating it will never work and whoever has tried it has failed. He said theirs no tech that will allow a seamless network handoff and called it a terrible idea that just doesn't work. Ironically, Khattak is now trying to do this very thing using a different implementation.
US Mobile's offer of allowing a second SIM to be added to devices so subscribers can use multiple networks without having to pay for two separate plans is a nice idea and good for consumers. However, having two networks on the same device is far from groundbreaking. And those customers looking to try and take advantage of getting a second SIM to be used in a tablet or another device as part of this offering should be warned, that your plan will get deactivated for doing so. Khattak explicitly stated this in reply to another Reddit user.