Network handover in Google Fi

&quot;but that doesn’t change the fact that Google has produced a service that works, is easy to use, switches quickly between networks,&quot;<p>I&#x27;ve had what can only be described as a hellish experience with Google&#x27;s Fi service since I got it. My bugs include but are not limited to:<p>- SIM cards randomly not being associate with both networks, the fix for which is clearing the Fi app data, restarting the phone, and then re-running the app. With wifi, which is tricky when your car breaks down on highway 1.<p>- Interment and VERY poor data performance, but no interruption in voice service.<p>- Data service working fine, but all incoming and outgoing calls failing.<p>In the support category, Project Fi has also been a nightmare. None of the support staff know what to do when you encounter a problem. They don&#x27;t know why my account (or my friend&#x27;s account) are broken. They&#x27;ve suggested (just to me) and had me do the following things:<p>- Reboot the phone.<p>- Reseat the sim card while the phone is on.<p>- Factory reset the phone<p>- Factory reset the phone again without the sim card in.<p>- Buy a new SIM card. They gave me free shipping, at least?<p>- Flash the phone to a version of Shamu that is not compatible with other carriers.<p>- Remove all other user accounts from the phone.<p>I&#x27;ve been repeatedly asking to cancel my service and get my number ported back to google voice, and I&#x27;ve actually had service reps ignore me claiming they want to explain &quot;[their] side of the story.&quot; I have a chat transcript explaining that.<p>And of course, let&#x27;s not forget the weird callback system bugs. Like last night 4 hours after I scheduled a call they called me 2 times at 1am, and when I asked them not to call me I was told, &quot;If you don&#x27;t want us calling then don&#x27;t schedule a service call!&quot; When I said I didn&#x27;t, they said, &quot;Well that&#x27;s odd because I see it right here&quot; then hung up on me.<p>I still have not successfully cancelled my Fi service. The web form version 500s.<p>I do not think it is very easy to use, or ready. It seems pretty terrible to me.

When Fi was announced they mentioned that public wifi traffic would go through a VPN to google&#x27;s datacenters. At the time I assumed that they&#x27;d just run ALL traffic through the VPN, since that&#x27;d make for some very seamless switching. As bad as that would be from a privacy perspective, I trust Google more than T-Mobile or Sprint.<p>By running everything through the VPN, you&#x27;d be able to have TCP connections that didn&#x27;t break when the network switched, since your device&#x27;s public IP address would be in a datacenter somewhere.<p>Also with a VPN you&#x27;d be able to send voice traffic over both a carrier connection and the wifi connection at the same time to avoid dropouts.<p>There is something similar called Multi-path TCP (MPTCP) which uses latency to decide which TCP path to send traffic over.

&quot;Given that two different profiles exist on the Fi SIM, the Fi software must have the capability to switch between them. SIM cards are actually little computers, so by developing an application that runs on the SIM card Google could trigger a switch based on any of the information the SIM has access to – the network it is registered on, the receipt of a trigger SMS, or something else.<p>My guess is that the SIM card contains a small application that can activate a specific profile in response to a command from the Fi software. This profile then remains active until another such command is received. Logically, this makes sense – the algorithms Google will want to use as part of the system are much easier coded as part of an app that can be updated through the Play Store and access any number of data sources; once it decides, it simply instructs the SIM to activate the desired profile.&quot;<p>More likely is that the SIM card just holds a few different profiles and custom software that runs on the baseband processor watches the strength of both networks and sends out of band messages back home to tell recycled Google Voice infrastructure how to find the subscriber. The switchover times you report are consistent with Google&#x27;s VoIP infrastructure holding a call and silently dialing&#x2F;connecting it on the other network.<p>It would be interesting to see if voice handoffs still worked if IP networking was unavailable on the phone.

Very interesting. This contradicts how Google advertises the service though. They say the transition is seamless. Unless they are playing fast and loose with the definition of seamless, this does not seem to qualify.<p>According to their website it is expecting signals to slowly get worse and have time to start transitioning before it drops out. A sudden loss of wifi for whatever reason probably confuses it. I would expect walking down the street away from your wifi would cause a smoother tansition.<p>I also expect those dialer codes are not meant for use during a call, and that is why a transition is queued up.<p>Have you tried driving from a Sprint deadzone, where you are on TMobile, to a TMobile deadzone where you would have to transition to Sprint? This would show if it can actually transition between the two during a call. Which others seem to say works.

<a href="https:&#x2F;&#x2F;republicwireless.com" rel="nofollow">https:&#x2F;&#x2F;republicwireless.com</a> provides seamless wifi-&gt;cell and cell-&gt;wifi handover of calls.

I&#x27;m pretty sure the testing methodology in this article is flawed. Using the manual switching codes (which are NOT recommended by Google) shouldn&#x27;t be used to evaluate the vast majority of situations. For instance, doing timing on a manual network switch isn&#x27;t necessarily equivalent to the phone automatically switching. Also, doing a manual switch and then extrapolating that the phone doesn&#x27;t automatically switch back is not valid.<p>Basically, you can&#x27;t test any of the automated functionality using manual codes!

I&#x27;ve been keeping track of Google Fi since it was released.<p>I&#x27;m hoping the new Nexus 5 (both LG and Huawei versions) is compatible with Google Fi, although I did call the Fi support number (and talked to a real human) and she said they haven&#x27;t heard anything about support for the Nexus 5.<p>Here&#x27;s hoping.

Another interesting future aspect of HetNet technology <a href="http:&#x2F;&#x2F;www.netmanias.com&#x2F;en&#x2F;post&#x2F;blog&#x2F;7388&#x2F;kt-korea-lte-h-lte-u-mwc-2015&#x2F;netmanias-interview-with-kt-at-mwc-2015-kt-s-demonstrations-of-lte-h-and-lte-u" rel="nofollow">http:&#x2F;&#x2F;www.netmanias.com&#x2F;en&#x2F;post&#x2F;blog&#x2F;7388&#x2F;kt-korea-lte-h-lt...</a><p>What GoFi is doing is actually not at all new and has been around a while (the wifi &#x2F; LTE hand off) the third provider is always been possible with multiple SIMS which has been around for quite a while.

T-Mobile does WiFi to GSM handover now. My phone has been doing it for two years. They have to; T-Mobile coverage has so many holes it would be useless otherwise.

Interesting; &quot;Data does not handover between networks&quot; seems to contradict other reports I&#x27;ve seen that the data connection seamlessly hands off.

I&#x27;m surprised that (it seems) google isn&#x27;t using Multipath TCP to carry the VPN traffic to google. This would allow it to switch seamlessly between LTE and Wifi and in theory even LTE and LTE while maintaining the VPN connection and thus the call.<p>In fact, Apple uses this tech for Siri to reduce latency on voice queries.

Have you tested HO between Sprint network and WiFi ?<p>As per our understanding Sprint doesn&#x27;t have VoLTE network so if Handoff is supported means Project Fi is VoIP.

I remember having UMA on a T-Mobile BlackBerry (8800, I think) and the call handoff from WiFi to mobile really was seamless, no gaps at all. This was in 2007, by the way.