Earlier this year Google announced Project Fi which is the company’s attempt at being their own carrier, even though technically the company would be piggybacking on Sprint and T-Mobile’s network. Now Google had stated that they planned to start off slowly and at the time of launch, they stated that only the Nexus 6 was the only phone that was supported.
Apparently this is because of the hardware used that allows it to work on Project Fi. However it turns out that might not necessarily be true. According to XDA forum member Robpol86, it seems that he has managed to get Project Fi up and running on his Nexus 5. Naturally we’re sure many have tried it in the past, but perhaps his method could be worth checking out.
According to him what he did first was activate Project Fi on the Nexus 6. He then took out Project Fi SIM Card and used a nano SIM to micro SIM adapter and put it inside his Nexus 5. He then proceeded to factory wipe his handset, although we’re not sure if this is necessary and from there he was able to proceed with setting up his Gmail accounts and everything.
So far it seems that everything is working just fine. “So far everything still works fine. I hardly make/receive calls though so I’m not a good candidate to test call handoffs. I made a call while on WiFi and then disabled WiFi and the call wasn’t affected at all. But I’m not sure if the call started on WiFi or not.” However he notes that whenever he makes a call, it drops him down to HSPA+ indicating that VoLTE does not work.
In any case we can’t guarantee that this will work for you, but if you have a Nexus 5 lying about and don’t mind giving it a try, hit up the XDA forums for instructions on how to proceed.