Alice cannot call Bob, Bob gets "missed call" notification

[czaviar]

I have:

• searched open and closed issues for duplicates
• read https://github.com/WhisperSystems/Signal-Android/wiki/Submitting-useful-bug-reports

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Bug description

Alice is trying to call Bob,without any success. When Alice terminates the calling, then Bob gets a "missed call" notification.

Steps to reproduce

• Alice starts to call Bob, she sees "Calling" screen
• Bob can't see any notification
• When Alice stops calling, then Bob gets only "missed call" notification

Device info

Alice Device: Xiaomi Redmi Note 4
***Bob Device: LG G3
Android version: 6.0
Signal version: 4.9.9

Link to debug log

Alice log: https://gist.github.com/czaviar/31f4f6d89c868f6f3040be097bf16f6f
Bob log: https://gist.github.com/czaviar/c9bbf249d84f87b9dc67b44a6598485d

[moxie0]

Bob's log is strangely filtered and cut off. Hard to tell from that, but it looks like something on the network is preventing a successful ICE handshake. Are Alice and Bob's clocks both accurate?

[czaviar]

Yes, they both have the same time from the cell provider.

[paulo-erichsen]

I had the same issue as OP, then I realized that it was only my phone that wasn't making / receiving calls. I ended up finding out that the problem was that my phone had an adblocker DNS66 running. Once I disabled DNS66, I was able to make and receive calls.

I'd be interested in knowing which host Signal uses such that I can just allow that host through the adblocker, without needing to disable it altogether

[billie80]

You can exclude specific Apps under the Apps tab instead of disabling DNS66 completely. If you just want the domain excluded using the hosts tab maybe you find the blocked host in the logcat output. It should also be hidden somewhere in the signal source code ;-)

[czaviar]

I do not have any adblocker installed.

[riyapenn]

Unsure of who Alice and Bob in this scenario are, but here are two logs from 4.10.12 for this issue:
Xiaomi Redmi Note 2 / Android 5.0.2: https://gist.github.com/a689695be31333c2ac4d78cb732e36b6
Huawei Y3 II Dual-SIM / Android 5.1: https://gist.github.com/2b098a591141d06f892b22737983d8be

[moxie0]

@riyapenn are their clocks synchronized?

[jmayday]

@czaviar I had exactly same issue. In my case problem was caused by Blokada app (http://blokada.org/). Just after turning it off Signal calls started working again.

[czaviar]

@jmayday Thanks, but I do not have any adblocker installed.

[alexanderadam]

@czaviar do you use a VPN? Or the people you want to call?

Even if some other application or configuration is causing it and it isn't solvable through the protocol itself:

Signal should ideally show the user(s) that for some reason no successful connection could be made. And maybe even give a hint to the user(s) like Some AdBlocker might be the reason. If you use one ensure that you whitelisted $host..

The device that doesn't get the call can obviously see that this is probably a technical issue because it never "rings" but shows the "missed call" notice afterwards.

PS: is Signal really dependent from synchronized clocks?

[czaviar]

No I don't. But once I switch on the VPN on both devices the problem dissappears.

[alexanderadam]

My guess: if it works when you are using the VPN it seems that your "native" network is blocking (and the VPN isn't).

[automated-signal]

GitHub Issue Cleanup:
See #7598 for more information.