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Comment by cyberax

1 day ago

Are you sure you don't have any misbehaving spam detectors? The voice circuits are VERY robust, low bandwidth, and cellular providers prioritize voice calls. There's just no reason to purposefully throttle the voice calls, the bandwidth savings would be negligible.

But it's possible that your cellular provider has misconfigured STIR/SHAKEN validation and/or some badly behaving spam call detection.

6 comments

cyberax

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edelbitter  1 day ago

Google is currently carrying out a "call screening" experiment on Pixel phone "owners" (mentioned, but cannot be disabled in the app settings). OP is specifically mentioning iphone, though.

  • nixosbestos  1 day ago

    What on Earth are you talking about? Pixel Call Screening has been around a while (~2 years, at least), and definitely can be turned off.

    • edelbitter  1 day ago

      Automatic call screening is available in just a select few jurisdictions where that would be legal. In the remaining supported countries, one would explicitly opt in or disable the feature altogether as they please. Last month some rapist mentality dev decided that I am no longer worthy of having that toggle in the settings because my consent does not matter. So now the toggle is hidden, the feature is on. (I can briefly regain control by resetting the phone app to factory defaults, but it keeps coming back.. until Google fixes their happy little mistake).

FireBeyond  1 day ago

Voice "circuits" are largely a thing of the past. Most cellular calls are VoLTE or VoIP directly (though I'm certain there's shaping/QOS/etc., in play).

On the spam topic though, it is, or was, a common tactic for some spammers to do just enough on the call initialization front to generate a missed call or similar without actually ringing a device, leave no VM, the goal being to prompt you to return the call. Though this doesn't fit with the time delay aspect.

  • cyberax  1 day ago

    They are still separated from the regular traffic (via VLAN/VxLANs/MPLS, whatever). So your device will have a separate hidden IP (IPv6 or IPv4) that is used ONLY for voice connections, and it's typically firewalled to hell and back.

    One significant reason is roaming and inter-provider calls. Internal calls can go through a fully IP-native network, but external calls often need SS7 singalling and arcane interconnects. And you really don't want your SS7 switches to be even pingable from the public network.

    BTW, one thing to check: misbehaving WiFi calling. It works by establishing an IPSec connection with the ISP's infrastructure for that hidden IP. It should not be possible on a cellular connection (because what's the point?), but given the decline in technical expertise, I'd also disable it to see if it helps.