Feature Request: VoCrossSIM aka "Backup calling"
it's in Settings > Network & Internet > Call & SMS
OK, I don't see the option, so I guess it's something the network operator has to support, am I right?
Has anybody got this to work as I have the same problem with Android 14 & Pixel 7?
I am in Australia & installed Graphene then set it up with physical sim (Aldi) & esim (Lebara), when physical sim was out of range it would use data from the esim, Network & Internet > SIMs > select physical sim & Choose network would display disconnected.
Then I have run Googles web flashing tool to put google OS back on the phone & when physical sim (Aldi) is out of range under Choose network it would display Aldi Backup Calling without me having to change any settings.
Anybody have any ideas how to fix it?
Have you tried switching the eSIM on and off?
When you turn the eSIM back on, there is a dialog: "Improve mobile coverage? Allow your device to automatically switch to..." This must be activated.
An alternative way is Settings> Network&Internet> SIMs>
"your eSIM"> Switch mobile data automatically.
Make sure that mobile data is also activated for this eSIM (same menu as above, "mobile data" toggled on).
I should add the model is Pixel 7 GVU6C if that makes any difference.
When I turn eSIM off & on I get dialog box for choosing SIM for mobile which is the eSIM so the eSIM has mobile data toggled on.
I have selected Switch mobile data automatically on the physical SIM as this is the 1 I was wanting to do backup calling, the eSIM doesn't give me this option.
Unfortunately, I can't say exactly what the problem is, but I can at least rule out that it's due to the eSIM. I have also tried the workaround described above with an eSIM - it works.
Your phone model shouldn't have anything to do with it either.
I think I tried every combination in the esim & physical sim settings, I couldn't get physical sim to "automatically switch data" to esim which I had working when using the stock OS.
It's as if I got routing / tunnelling issue between the esim & physical sim.
- Edited
Any updates on this issue? No Backup calling toogle available on Pixel 7 Pro with latest GrapheneOS and two SIMs: physical and eSIM. WiFi calling works for the eSIM, but it can’t use physical SIM data connection for calls.
+1. This is needed. The above instructions do not appear to work and the Backup Calling feature is unavailable. It's available on the stock pixel 6a Android.
- Edited
I have a Pixel 7a.
Can confirm that Backup calling does not work for me on Grapheneos. I reinstalled stock pixel os to check, and backup calling worked immediately when toggling "switch mobile data automatically".
Back on Grapheneos now, still doesn't work.
EDIT: I suppose one of the issues here is that it might be difficult to debug this for developers, because in order to trigger a situation where you can test this, the SIM card you want to utilize backup calling for cannot be within coverage of it's native network. Any non-US developer can get a Tello US eSIM to test from outside the US. I'd be willing to donate to fund this.
@Murcielago, can you confirm that "Switch mobile data automatically" still works for you, including being able to make voice calls from the one SIM while using the other SIM's data? If so, might you be in a position to say which two carriers are involved and which "hardware SKU" you have?
@twine6148, can you confirm you don't see "switch mobile data automatically" on GrapheneOS with two specific carriers? If so, can you say which hardware SKU you have?
can you confirm that "Switch mobile data automatically" still works for you, including being able to make voice calls from the one SIM while using the other SIM's data? If so, might you be in a position to say which two carriers are involved and which "hardware SKU" you have?
Yes, i can confirm that. I have just tested it again and both points you mentioned seem to work.
My hardware SKU is GC3VE (Pixel 8 Pro) and I'm using european SIM-cards (If you have any further questions about carriers, please give me a way to DM you).
- Edited
@de0u
No, I indeed see the "switch mobile data automatically" on Grapheneos, and I can toggle it. Phone service and data usage while in a call works as expected. That's not the problem. Visually there is no difference, the only difference is that the cell phone carrier says "disconnected" instead of switching to "#carrier# backup calling"
GHL1X - Pixel 7a.
EDIT: I should clarify this. The reason I know that the "switch mobile data automatically" part works as it pertains to data while in a call is because I use two eSIMs on a daily basis, to provide optimal in-country service. Both domestic providers. This works fine, but one of them is a data-sim only and thus there is no backup calling to be expected.
That is however not why I chimed in to this thread. I recently went abroad and disconnected one of my SIMs and activated a different foreign SIM before leaving without turning on roaming. I can still toggle "switch mobile data automatically" in that situation, and as expected on the stock os, the SIM worked with backup calling. But not on Grapheneos.
And wifi calling works as expected, just to clarify.
- Edited
Can you confirm that the other SIM-card is actually in backup calling mode and not merely roaming?
See attached photo that I shamelessly found online, the carrier under "choose network" should say "#carrier name# backup calling".
https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcR_xSz9GBWCiSftRF4rGimMJPY6Ph1Vu6TL3Q&s
- Edited
Unfortunately I can't see your picture, but I looked for the symbol for “backup calling”. I don't have this icon in the status bar.
My test setup (both eSIM) is as follows:
- card A (old prepaid card) without credit (no internet possible because no credit)
- card B prepaid with credit
When I activate card A, I immediately see a “!” in the mobile network bar (similar to here).
If I activate card B, the second Network icon for card B shows up in the status bar and the exclamation mark on card A network icon disappears.
However, I've just noticed that it seems to make no difference whether I activate “Switch mobile data automatically” on card A or not - so I'm not sure any more how helpful my statement really is.
Well this feature is a little confusing. I've attached a link to the picture, hopefully that works.
The thing is, here in Europe it's basically redundant because we can roam in all other EU countries without paying any extra. But it makes a big difference when travelling outside Europe.
If the picture works, you can see the carrier name changes. And I believe the same thing is true if you pull down the notification drawer and checks the carrier name there. It will include "backup calling" if it works.
Still doesn't work for me on Android 14,
graphene version 2024090400.
Would be nice to have backup calling.
I tried this guide: https://github.com/kyujin-cho/pixel-volte-patch/discussions/272,
even read the linked code with the comments about the required conditions (which were true in my case) and it still doesn't work. Is ImsMmTelManager.java patched in some way in graphene?