Pixel 3xl drops calls after half hour

[Jengoddard]

My pixel 3xl drops every call (made or received) after exactly 29 minutes and 50 seconds. I don't know if this is related to phone settings, network or what so wondered if anyone had had similar issues or knew of a fix. It's a real pain in the backside as currently working from home and means I get cut off in every conference call!

[Mozzer321]

Putting it on hold worked for me on my Poco F3 as I had a call lasting way over, but after that my internet icon at the top of the screen only displayed H+ or 3g for the rest of the call, so is this putting on hold just switching me somehow to the 3g network? The internet icon switched back to 4g/5g once the call had finished. Weird and if it's switching to 3g then it's not a workaround when they switch off the 3g. Any thoughts?

[PayPro]

Try putting your phone into flight mode and then manually switch on WiFi. This will force the call over Wi-Fi and not be able to drop down to 3G. It will be interesting to see what results that produces.

[Baysik]

I first used the hold to avoid redialing at 29-50. This was at the start of January. I've been trying all the other options you guys are finding and as far as I know the hold switches off the cut-off. 

It doesn't alter the call type.; I think that's down to the mast/ network in response to traffic volume? I've had calls dial out on 4G and drop to LTE before the other end picks up. If I've got a good 4G call I use the hold and I've not seen it go down in response to that.

[PayPro]

@Baysik, are you sure you are not experiencing what @Mozzer321 is reporting? Calls cannot drop from 4G to LTE because 4G is LTE https://www.vodafone.com/business/news-and-insights/glossary/what-is-lte.

Are you able to try making a Wi-Fi call in flight mode to see if your hold hack works in those circumstances?

This disconnecting issue is almost certainly down to the fact 4G calling (AKA VoLTE) and Wi-Fi calling both carry the voice call over the data channels and it is likely that a session timer somewhere is instigating the call dropping.

[alexvanwijk]

Interesting - having successfully tested the workaround where you place the call on hold, I am now finding that I am experiencing the issue no longer. I spoke to my mum just now and saw that I had gone several minutes over the 29m50s cut-off of doom.

Has anyone else found the same?

[mdc1983uk]

Fantastic that a customer has found a solution that seems to work. Sadly for Voda that was way late for me to still be a customer. Thinking back to when I was, I used to use merge calls a lot and that involved putting one on hold and adding another call in. Maybe my problem didn't suddenly appear as I thought and it was always there just not present on the merge calls hmm.

I suppose it's a decent workaround that doesn't involve changing to 3G. Why they can't just sort it out though is beyond me!!

By the way for the people saying LTE is 4G that is of course correct. But some phones show LTE instead of 4G. Mine shows 4G but then switches to 4G+ when I use data. Some show LTE then 4G+. It depends on the brand and the firmware and whether data is being used whilst on a call. Likewise with 3G some show UMTS, 3G, H, H+ even DCH+ or combinations.

[chistery]

It's a workaround, not a solution.

A solution would involve Vodafone fixing the problem for good, something we know they won't do.

[repask]

UPDATE 16.2.2023 & 17.2.2023

Vodafone forum admins have decided to remove the screenshots showing my communication with Vodafone representatives on their official Vodafone Messenger channel. The message confirms that their Vodafone engineer confirmed the issue is down to SIP Session Timers incompatibility between Vodafone systems (SBC) and my Google Pixel 7 Pro and that they will open a case with Google to troubleshoot this further.

I have uploaded it again and included an external link for reference.

This is a shameful practice that they are willing to go to this length to hide the facts that they confirmed!!!

Original Post:

I have been testing this issue with the Vodafone network team for the last month and they have confirmed that the problem of calls disconnecting at 29 minutes and 50 seconds is due to SIP Session Timer Refresh incompatibility between the Vodafone SBC (their internal system handling the call) and my Google Pixel 7 Pro handset. Specifically, Vodafone SBC does not like the format of the SIP session Timer Refresh the Google Pixel 7 Pro sends before 29 min and 50 seconds expiry and because nothing comes back in response, the call session is then terminated.

I was told that the Vodafone engineer has raised a case with Google and is awaiting their feedback on how to resolve this.

Please see attached screenshots from communication with the Vodafone team on Facebook Messenger, confirming the above.

-- This screenshot below showing my communication with Vodafone via Facebook Messenger was removed by Vodafone forum admin to hide the truth that they acknowledged and know the issue is due to SIP Session Timer Refresh not working between their system (SBC) and customers' phone. Screenshot Uploaded again on 16.2.2023 7:53PM -- and again on 17.2.2023 4:08AM --

Reddit URL link to the conversation screenshot, just in case Vodafone forum admin removes it again: 

https://www.reddit.com/r/Vodafone/comments/113zbx2/vodafone_uk_call_disconnect_29_minutes_50_seconds...

Full transcript of Vodafone reply from Vodafone/Rachel:

I appreciate your concerns over the length of time this has been investigated for, Patrik. For an understanding on what is happening with your network case, I have copied the engineer's most recent investigation notes to date: Tracing examples provided, I can see that call ends after around 29 minutes and 54 seconds. This seems to be related to the device in how it tries to renew the SIP invite session. I have gathered traces and engaging terminals to try to replicate and investigate further. Following which this may need Google's engagement. We have been advised that there will be another update tomorrow, and will relay the recent information that we have from the engineers to you. Again, I do apologise for any inconvenience caused, I have set a reminder on this conversation tomorrow, for us to reach out to you. Rachael

THE SCREENSHOT WAS REMOVED BY VODAFONE BECAUSE IT SHOWED THAT THEY CONFIRMED THE ISSUE IS WITH SIP SESSION TIMER REFRESH FAILING.

YOU CAN SEE IT HERE OR IN THE REDDIT POST LINK ABOVE WITH THE FULL ORIGINAL POST BEFORE VODAFONE BLOCKED THE SCREENSHOT OF THEM CONFIRMING THEY KNOW WHAT THE ISSUE IS.

https://imgbox.com/vukB2r4o

Update from Friday 10.2.2023

Update from today morning (16.2.2023)

To put things into perspective. I work in telecommunications for the last 15 years and specialize in SIP protocol, SIP trunks, SBCs, phone systems, call centre solutions and more.

We face these issues with SIP communication protocol on a daily basis when deploying new SIP trunks for client call centres and other systems. It's a normal part of the deployment and to resolve these issues a configuration has to be modified on either end to match what each side is expecting to receive. In the case of the SIP session refresh, this is a setting that the Vodafone SBC ask for to make sure the call is still live. Otherwise, you could end up with 1000s of calls that didn't disconnect properly and would be hogging the SBC SIP channels, meaning it couldn't process any more calls, because of old stuck calls.

The SIP session refresh timer gets rid of these stuck calls because if the other side (my Google Pixel 7 Pro phone) does not reply in time (the SIP expiry timer is set by the SBC at the call start), the SBC assumes their is nobody on the other side and tears down the call. Even though you are in the middle of the call talking to someone.

The requirement on which side needs to refresh the timer (my Google Pixel 7 Pro or the Vodafone SBC) changes depending if you are on an inbound call (receiving a call) or making a call (dialing out). There are many times cases where one direction of the call works fine because the side that needs to refresh the SIP session timer actually does it correctly and the other side accepts it. In other cases, neither direction works because neither side like the way the SIP session timer refresh message is formatted (what configuration and messages it includes) and it discards it as if nothing was sent in the first place. This then results in a call hangup at the agreed time at the beginning of the call, in the case of Vodafone, their SBC is configured to expect a session timer at 29 minutes and 50 seconds and if it doesn't arrive (or it doesn't like the format) it disconnects the call.

I have now tested the suggested workaround with putting the call on hold before the 29 min and 50 seconds mark and it DOES WORK!

The reason is that when you put a call on hold, the Vodafone SBC is told to put it on hold, this results in message playback to the other side (you've been placed on hold, please wait) at which point the Vodafone SBC sees the SIP session timer refreshed because there was activity it needed to do.

The question for the Vodafone networking team is:
What is the difference in the SIP session timer refresh format during a normal call that is received before the expiry of 29min and 50 seconds, which the Vodafone SBC does not like and disconnects the call, and a call that is put on hold before the expiry that triggers another SIP session timer refresh and Vodafone SBC accepts that one without issues?

Inspecting the difference between SIP session time refreshes in these two call scenarios will help Vodafone to move closer to resolution.

The new configuration that will resolve this issue can be applied to either side, the Vodafone SBC firmware or Google Pixel 7 Pro OS (Android 13). This is because all that is needed is for both sides to accept what either side is sending and receiving. Currently, Vodafone SBC does not like what Google is sending, thus it drops it and ignores it.

Because this issue is affecting so many different models of phones, this is not something that Vodafone can keep asking manufacturers to keep matching what Vodafone SBC expects to receive to refresh the SIP session correctly. The solution should be by modifying the Vodafone SBC config to finally accept the SIP session refresh timer format from all of these different phones.

Either way, this is not rocket science when you work with these technologies and I have full confidence Vodafone engineers know this. The reason they are not fixing it is either because their Vodafone SBC is incapable of accepting the format of SIP session timer refresh messages that all these phones send. This could be because the manufacturer of the SBCs they use (Ericsson, Huawei, Alcatel or whatever they use) is not willing to release new firmware updates and then Vodafone engineer is left with asking Google, Apple, Samsung etc. to try and match what Vodafone SBC needs to receive for the call to work. You can see how slow that process will be when you reach out to these large companies with millions of handsets to change something to fit one provider that has issues because of the hardware (SBC) they use.

So all in all, I hope Vodafone will stop saying that this issue is not on their side, they will come out with confirmation for everyone that this is a known issue affecting specific phone models and what is the plan to fix this. Because as I said it can be fixed by either side Vodafone or phone manufacturers. I know which side (Vodafone) is providing us with a service that does not work and is responsible to fix it. Pushing this issue onto manufacturers of phones is going to take a long time to change.

Thank you,

Patrik

[mdc1983uk]

@repask  Agree with everything you said I was talking about session timers a year ago. Just shows they are willing to lie even more someone else got told it was down to Qualcomm chipset in phones!! It appeared true because someone had problem with a Sony and Oppo and I checked the specs and they were both Qualcomm. And mine and Kayleighs Xiaomi/POCO have Qualcomm same phone with 2 different labels. But I see Pixel 7 Pro has a custom Google chipset made by Samsung no Qualcomm in sight.

I don't even understand anymore what the problem can be stemming from there is plenty of Android phones that don't have the problem yet many do. So Google shouldn't have to fix it either. As you say manufacturers shouldn't have to either because it doesn't work whether your phone has Voda firmware or not.

They are nuts letting this drag on for so long, and as I said before they better not even consider merging with Three unless they either take over their systems which work or fix this first. It's pathetic they appear to be the only network in the world let alone UK that can't support a good chunk of the Android devices even a Google made flagship device. And they still sell these phones online and in stores knowing full well they aren't fully compatible with the network it's barmy.

[repask]

@mdc1983uk 

Have you seen that they removed the first screenshot from my original post showing the Vodafone rep acknowledged that they know the issue is due to SIP Session Timer Refresh not working?

I have just re-uploaded it and posted it on Reddit as well. This behaviour is unacceptable. Let's see how long they will leave the two screenshots up in my original post.

https://forum.vodafone.co.uk/t5/Android/Pixel-3xl-drops-calls-after-half-hour/m-p/2725999/highlight/...

If Vodafone removes it again, tag me in a post and I'll upload it again.

How can they have the audacity to edit the truth from a forum that deals with this problem?
This just confirms they know they can not fix it and are simply hiding the truth. UNBELIEVABLE!!!

What is most likely happening ist that they found out that Vodafone SBC's can't be configured to accept SIP Session Timer Refresh messages in a certain format and now they are left with 3 options:

1) Acknowledge that they can't support WIFI Calling and 4G VoLTE on some devices due to their poor SBC hardware used inside the network

2) Acknowledge they need to wait for the SBC manufacturer to release a new firmware version for the SBCs with a fix, which might never happen, otherwise, it would be fixed already years ago

3) Play dumb and ignore the issue hoping it will go away so they don't have to lose market share and refund peoples monthly contractual payments that are affected by this

I think sadly they have chosen Option 3)

To have the audacity to publicly lie and remove their own messages from my post that confirm what is the issue is criminal!