VOLTE calls drop after a period of time

mine21

Thanks to the awesome people involved with development and support.
I have a Pixel 10a with up to date GOS.
My carrier has VOLTE but it's not officially supported by google yet, so I had to enable it with carrier overrides.
The phone registers with IMS and everything looks intact.
The problem is: Incoming VOLTE calls drop exactly after a minute and 45 seconds while outgoing calls drop exactly after 29 minutes. no problem with 3G calls.
I have another phone, same carrier with MTK chipset and VOLTE works smoothly. (I was able to enable VOLTE through engineering mode)

Will appreciate any help
Thanks
mine21

de0u

mine21 Naming the carrier might help. In general, more details is better than fewer.

mine21

Sure, thank you
carrier_id {
canonical_id: 2694
carrier_name: "XPhone"
carrier_attribute {
mccmnc_tuple: "42521"
spn: "xphone"
}
}
Appears in: https://android.googlesource.com/platform/packages/providers/TelephonyProvider/+/android17-release/assets/latest_carrier_id/carrier_list.textpb
I cross checked with ##4636## and it is actually the carrier id

Please let me know if you need any other details
Thanks a lot

de0u

mine21 carrier_name: "XPhone" [...] mccmnc_tuple: "42521"

Is that xphone.co.il?

Is it possible to borrow a SIM from somebody that is on a carrier that Google believes supports VoLTE?

mine21

de0u XPhone.co.il is correct.
A sim from a different carrier (i.e. Hot Mobile) works with no problems. I didn't have to enable overrides, VOLTE was available right away.
On XPhone both a sim and an esim had the same issue. Currently it's an esim.
I've tried adding an apn ims settings for XPhone found on an apn list on android source code - didn't help.
Thank you

de0u

mine21 It is possible that Google isn't supporting VoLTE on XPhone because there is a problem with XPhone's implementation of VoLTE, perhaps some disagreement between Google's cellular modem firmware and XPhone's system. If something like that is going on, I don't think the GrapheneOS project is in a position to do much, especially without a way to test against XPhone cell sites.

The GrapheneOS carrier overrides can help users when the sole issue is that Google's carrier configurations are blocking VoLTE use that would otherwise work fine. If there is an actual problem, the overrides can't fix it.

I wish I had better news...

Please note that I do not speak for the GrapheneOS project.

mine21

de0u Thanks
So basically if any update by google fixes the problem it will be automatically implemented by GrapheneOS?

Is there anything I can ask XPhone's tech support to check for?

I'm a bit familiar with applications like Tower collector and websites such as www.cellmappear.net if any information might help, please let me know.

Appreciate your time
Thank you very much

de0u

mine21 So basically if any update by google fixes the problem it will be automatically implemented by GrapheneOS?

Probably? I believe GrapheneOS makes updates based on Google firmware and carrier configuration information. And meanwhile if XPhone fixes a problem it will probably start working automatically.

mine21 Is there anything I can ask XPhone's tech support to check for?

If possible, make sure that a Pixel running Google's stock OS doesn't use VoLTE on XPhone. Then tell somebody at XPhone that Google's Android on a Pixel doesn't use VoLTE, and that if you override it on via GrapheneOS it works for so many minutes and then stops. It is quite possible that they already know that it doesn't work. Or perhaps they would be interested in gathering data while you make a call.

mine21

de0u They've already told me that VOLTE doesn't work at all on pixel phones, and where a bit surprised that I was able to enable it (due to override in GrapheneOS).
According to them, they're trying for a while to contact Google in order to solve the issue.
They had no idea what to do with these specific call drop issues.

I don't really expect much from them as I don't think their expertise is on par with people on this form.
I'll try telling them about data gathering and keep you up to date in case it might help other people.

de0u

mine21 According to them, they're trying for a while to contact Google in order to solve the issue. They had no idea what to do with these specific call drop issues.

I don't know how to advise a carrier how to deal with Google.

I do think it's possible that if they turn on logging for your number at one of their cell sites and have you place a call and watch the call drop then they might learn something.

mine21

de0u My carrier support wasn't helpful.
Meanwhile, I've found this:
https://www.telecomhall.net/t/volte-calls-dropping-after-30-minutes/28227
Can it be a setting in carrier overrides?
Are there settings I may change by myself (maybe through adb)?
Thanks

de0u

mine21 My carrier support wasn't helpful.

I'm sorry to hear that, but carrier action may well be required to address this issue.

mine21 Meanwhile, I've found this:
https://www.telecomhall.net/t/volte-calls-dropping-after-30-minutes/28227

That is interesting, but it's not immediately clear where to go from there. Perhaps posting this issue there might help, though I am skeptical.

mine21 Can it be a setting in carrier overrides?
Are there settings I may change by myself (maybe through adb)?

At the end of the day, if the carrier decides to disconnect a call then the call will be disconnected. We don't know yet whether the disconnect is on the carrier or the Pixel. It is possible that some tweak on the phone might work, but that is not certain. It is not clear anybody here will be able to help with that.

mine21

de0u Surprisingly, one of their engineers that actually work on it just called me.
He was familiar with these call drop issues, has access to logs, and According to him, it should be solved In the coming weeks.
They're still trying to get it to work on vanilla android (or on GrapheneOS without enabling overrides).
Thank you