Unlocked Phone - Manually switch carriers on Fi?

[kjhee43]

I have searched and searched and was surprised I couln't find the answer to the question so I am going to ask.

I am currently using Verizon with and unlocked phone that works on all 4 major US carriers. I am thinking of switching over to Fi. I have read about how only the phones "designed for Fi" get teh automatic carrier switching, etc. So my question is:

If i have an unlocked phone that works on T-Mobile, and Sprint (and Verizon which i am using now), and i put a Fi sim in it, can i use an app like signal spy to manually switch networks instead of letting it auto switch?

If not, why?

 

[hallux]

That depends on what phone you have. If you have a phone that is FULLY supported (designed for Fi), yes. Fi will work on any phone that works on T-Mobile, and will use only T-Mobile towers if it is not fully supported / designed for Fi.

Fully supported phones are the following:
Any Nexus or Pixel phone
Moto G6 and G7
LG G7 ThinQ and LG V35 ThinQ
Moto X4

Any other device will only work on T-Mobile towers if set up with Fi. Just because your device CAN work on Sprint or T-Mobile does not mean Fi will support carrier switching on it if it's not one of the designed for Fi devices.

 

[kjhee43]

Right now I am using a moto z3 play. It is not a "designed for Fi" phone.

Just because your device CAN work on Sprint or T-Mobile does not mean Fi will support carrier switching on it if it's not one of the designed for Fi devices.

Why is that? If it CAN work with Fi, why won't it?

 

[hallux]

Why is that? If it CAN work with Fi, why won't it?

Because the "designed for Fi" devices have a Google-controlled network stack that allows Google to support the switching. I can't say that a Fi-sourced version of a device is different from the same device from a carrier, it may be that the manufacturer has allowed Google to provide that part of the software for all of that model.