back to article Accidental homicide: how VoLTE kills old style call accounting

Korean and US telco researchers have sounded what's probably the first death-knell of voice calls, demonstrating a variety of problems – some fundamental – with how Voice-over-LTE (VoLTE) works. The Carnegie-Mellon CERT has wrapped the problems up in this advisory, based on this ACM paper. The problems, which we'll describe …

  1. Ru'

    No doubt, as technology leaves their antiquated business model in the dust, they will turn to legislation instead of changing anything. Nothing like turning customers into criminals just to preserve the status quo...

  2. jonathanb Silver badge

    Sending data over a voice call session isn't a new idea, it is how we used to do things before broadband was invented.

    1. Paul Crawford Silver badge

      And now its the other way round. Such if life...

  3. Paul Crawford Silver badge

    Actually anything that marks the death-knell of "premium numbers" and stupidly over-priced foreign calls is a good thing!

    It can't be beyond the wit of the telcos to have a reasonable model for data based on some monthly minimum and some reasonable extra for large amounts of data that will keep the lights on. All we need is some honesty in advertising and a regulator willing to beat them until the comply.

    1. Steven Raith

      "Actually anything that marks the death-knell of "premium numbers" and stupidly over-priced foreign calls is a good thing!"

      You don't actually expect that to happen, do you? Much as though you are technically correct, they'll find a way to keep gouging for different codes.

      Steven R

    2. Anonymous Coward
      Anonymous Coward

      As somebody whose mortgage was paid for many years by the development of IVRs for the adult premium rate industry, I think calling for the death of PRS is slightly excessive.

  4. Pascal Monett Silver badge

    Interesting article

    So voice calls are (badly) handled with an outdated model for accounting purposes.

    In Luxembourg (where I work), I have a company phone with a 15GB data plan. Any call to any Luxembourg number is free. I have the option of declaring a favorite country (fyi : in Luxembourg, border workers are ten times the amount of national workers). Obviously, living in France, I declared that as my favorite country. Calls made to French numbers are thus free as well. I do pay a small amount for international SMS.

    Basically, the only thing I see making money for my telco is the monthly allowance (and, at €40, it's not so much compared to what I've seen elsewhere), and the international calls I have to make from time to time (other than France). Oh, and premium numbers, obviously.

    Seems it is possible for a telco to make a living without scrounging every last cent from its customers after all.

    1. goldcd


      "Better, in the long run, to sell data pipes to mobile users and bid a fond farewell to the old model." - which I suspect is pretty much what we all want anyway.

      Resistance comes from within the older telcos. There are a lot of people whose jobs depend on the complexity that's built up. Should their employer just decide to:

      1) Build a network

      2) Solely sell flat-rate dumb data-pipes to this network

      A lot of people are unemployed.

      Mobiles companies are terrified about becoming these dumb-pipes - hence all these weird pay-by-bonk apps that as you travel loads seem to be pushing (despite nobody wanting/asking for them).

      Fortunately it's inevitable. Hurrah.

      1. Bronek Kozicki Silver badge

        Re: Indeed

        Luckily there is some competition between mobile networks, so they need to watch the costs, and cutting the jobs associated with "legacy technologies" is an obvious way to go. It will take a long time however - as long as 2G (and 2.5G) networks are used, these "legacy technologies" are not actually legacy, they are used by current clients who need support (billing etc.)

        1. Alan Brown Silver badge

          Re: Indeed

          "It will take a long time however - as long as 2G (and 2.5G) networks are used"

          Analogue mobile went away a long time ago. How many 2G handsets are left in service?

          1. Anonymous Coward
            Anonymous Coward

            Re: Indeed

            Quite a few, given 2G EDGE still exists as a fallback in case 3G HSPA and 4G LTE connections don't work. But I think that's where they draw the line. I haven't seen a 1G GPRS connection work on a smartphone.

            1. jamesb2147

              Re: Indeed

              I have, unfortunately, seen GPRS on a smartphone. ATT's US network used to not be so great in my area. It's been years since I tried it, though.

          2. jonathanb Silver badge

            Re: Indeed

            I can see 2G potentially surviving longer than 3G. 2G's advantage over 3G is better coverage for the same number of masts, but other than the ability to make voice calls, there aren't any advantages of 3G over 4G, and voice calls aren't any better over 3G than 2G.

      2. John Hughes

        Re: Indeed

        A lot of people are unemployed.
        How? Voice networks haven't used people to switch calls for quite some time you know.

  5. jzl

    Details, details

    The fundamental economics is governed by supply, demand and cost of provision.

    So it doesn't matter whether telcos charge per minute of calling, or per megabyte of data. The net result will be that the market will decide the total amount of revenue per customer and the profit margin available. The specific charging model is just details.

  6. Paul Shirley

    sip already made 3g voice overpriced

    My last 3g Android phone was quite capable of making SIP calls at below payg voice rates on my carrier, only the traditional shocking prices of payg data came close to matching the equally abusive price of voice. This is not an exploit and its to late to pretend it can be stopped.

    1. Warm Braw Silver badge

      Re: sip already made 3g voice overpriced

      Indeed. I read "No need to place calls through the operator's SIP server" and thought "how could that possibly be described as an attack?". It's all just data. Admittedly on a congested base station you might need some QoS guarantees to make your call intelligible, and you might be prepared to pay for that or you may not and choose to call later, but that kind of billing would be a lot easier to calculate and to justify.

  7. Francis Vaughan

    Old style acounting, and old style plans

    Who has a mobile phone plan where they actually end up paying for individual calls? Seems most telcos and resellers are selling plans that feature some idiotic number of calls "for free" in the plan and then simply use the call count as a way of pushing you up a tier in the plans if you actually make a lot of calls. Under almost all usual circumstances you never actually pay for metered calls.

    Getting rid of premium numbers OTOH would be the proverbial good idea.

    1. Paul Shirley

      Re: Old style acounting, and old style plans

      In Britain (and I believe EU) we have a surprisingly large proportion of PAYG users, so many the carriers sell the same types of bundles prepay users get. But many of us do pay for metered voice.

      I think what has the carriers really spooked is 1: even on PAYG rates it can be cheaper to use VOIP, 2: VOIP works on free WiFi and that's become almost universal, completely cutting them out. Carriers here have all launched VOIP apps that charge voice minutes against your 'allowance', even if you make the call over WiFi, quite astonishing they think they'll get away with that little scam for long.

      1. therebel

        Re: Old style acounting, and old style plans

        Taking the call time from your allowance when making a call over WiFi may seem a bit cheeky but you are still using their network. With a normal voice call your phone is connected to the nearest base station and the call is sent using their network. With a WiFi call (not Skype etc but a proper WiFi call now being introduced by EE in the UK) you may be using your broadband but that is still connecting the call through to their network and on to the end user.

        I don't disagree it seems a bit of a scam but it only skips the first step of a standard voice call, the rest of still the same.

    2. Vic

      Re: Old style acounting, and old style plans

      Who has a mobile phone plan where they actually end up paying for individual calls?

      I do. For my usage pattern, it works out a lot cheaper that way...


  8. jake Silver badge

    POTS still works quite nicely here.

    I don't do "cell" calls, unless it's an emergency.

    I mean, really, why always the cell? Is the entire public cellular userbase so wrapped up in itself, and afraid that it might might not be important in the great scheme of things, that it absolutely HAS to make itself known, constantly, with useless trivia?

    This is not what we invented computers and networking for.

    1. Anonymous Coward
      Anonymous Coward

      Re: POTS still works quite nicely here.

      We didn't invent computers and networking for... communication and information processing?

      I guess next you'll tell us that cars and roads weren't invented for transportation.

      1. jake Silver badge

        Re: POTS still works quite nicely here.

        "We didn't invent computers and networking for... communication and information processing?"

        I did not say that. What I said was that POTS was invented for humans to interact one-on-one. It still works admirably in that role. The entire so-called "smart-thingie" marketing bullshit has completely disassociated the human aspect of that one-on-one interaction.

        1. John 62

          Re: POTS still works quite nicely here.

          The story is told that Alexander Graham Bell actually wanted to use the telephone to broadcast opera and one to one communication was an afterthought.

        2. Anonymous Coward
          Anonymous Coward

          Re: POTS still works quite nicely here.

          "This is not what we invented computers and networking for."

          The context was of a discussion of networking and computers in relation to communications and data processing. Your rambling about the POTS aside, what you stated was quite simple: we didn't invent computers and networking for cellular communications. Except cellular communications are a nearly perfect example of the sort of challenge that networking and computers were invented to deal with.

          Perhaps if it were all piped through ring 0 you wouldn't have a problem with it?

  9. Trollslayer Silver badge

    Dynamic IP address?

    The IP address is not guaranteed to be consistent so this isn't a silver bullet.

    1. Charles 9 Silver badge

      Re: Dynamic IP address?

      Easily solved with a DDNS entry. Granted it's a slight additional expense, but it can be worth it if you're on the move a lot.

  10. This post has been deleted by its author

  11. Preston Munchensonton

    Free calls are neither free, nor calls

    That makes getting free calls a cinch: modify the voice application so the server doesn't see the message (for example, by sending the message directly to the caller's IP address instead of back to the server).

    If we follow this example through to its logical conclusion, several details should become obvious:

    1. You are now paying for the data usage and not the call usage, as VoLTE is a data-only service with VoIP on top. The calls will never be free.

    2. Direct, peer-to-peer calling or messaging doesn't change anything for the carriers but the call accounting. Excluding the SIP server from handling the calls is just fine, since those calls wouldn't hit the Public Service Telephone Network. No PSTN = no Call Detail Record.

    3. If you really expect to manually punch in someone's IPv6 address to ring their mobile, be my guest.

    In the end, this is possibly the dumbest storm in a teacup that I've heard this week.

    1. Paul Shirley

      Re: manually punch in someone's IPv6 address

      Android already has that covered (a little), to call my home SIP line (no DID) I just use the contacts book as normal... if it ever becomes necessary to use IPV6 raw addresses contacts will have support added. They might already, never bothered checking ;)

      Does anyone punch in numbers more than once anyway?

  12. Anonymous Coward

    The phone network

    Kill it with atomic fire!

    Enough of this nickel-n-dime BS already. And the panopticon-friendly privacy model of course.

  13. Joe Harrison

    But even when you are no longer making "calls"...

    ...they'll still want to make you pay Line Rental.

    1. Badvok

      Re: But even when you are no longer making "calls"...

      Sorry I don't get your point, in the UK at least, you don't pay line rental on mobile networks whether your using data or voice or SMS.

      I know you do however on fixed lines and other physical services like electricity, gas, water but that's because there is a fixed physical connection aka line that you are renting.

  14. IP

    Voice has been data since networks went digital in the 90s, and as long as the carriers control the cell networks and can monitor its protocols they can bill for whatever they want. Re VoLTE it is not rocket science to lock down the smartphone standard dialler to use SIP only towards specific operator IPs / soft switches. This has already been done for 2-3 years with carrier wifi dialling in the US as supported by Sprint and T-Mobile. And I am not aware of anybody who has jailbroken or hacked the dialler for either Android or iPhone as suggested feasible by this article. Such apps would also be immediately rejected from app stores...

  15. Crazy Operations Guy

    Just charge for QoS levels

    Why not just offer a dumb pipe and then charge based on QoS tag of the packets going across the network. That way TelCos can still get some cash for voice calls albeit in a round-a-bout fashion by charging for the higher priority. User would be able to pay the tariff for any data the want (So if you absolutely need a file downloaded, you can bump its priority and get better speeds in exchange for a slightly higher bill). Essentially you'd have something like $0.01 per megabyte of low-pri data, $0.015 for high-pri data and $0.02 per high-pri megabyte no matter what is running on top of it.

    1. jamesb2147

      Re: Just charge for QoS levels

      The issue I can foresee here is twofold:

      1) Communicating how this works to users. Talk about a nightmare.

      2) Congestion is rare enough that you'd actually have to gouge users something fierce when it happens, and that's about the only time QoS matters, at least on wired networks. I suppose giving higher transmit priority to higher QoS levels would be an alternative, but current models aren't built for it.

  16. jamesb2147

    QoS is the point here -- I have $10 tablet data plan I run my phone off of

    The researchers' points were valid, El Reg is an entertainment organization because society doesn't know how to separate out information services and entertainment, and QoS will be what we probably all end up paying for because you can't fake that and it's easy enough to track.

    My SIP calls are fine about 60% of the time without any QoS on my Verizon LTE connection in suburban USA. The rest of the time I have to repeat things frequently or ask the other side to repeat themselves. I'm actually thinking about getting a couple of wired SIP phones for the house and office for when I need a reliable voice connection (not as often as you'd imagine, given the prevalence of email, and I work at a University where people absolutely HATE email). I'd be willing to pay slightly more for a more reliable data connection for phone calls (read: better QoS) on a per-minute basis, but I doubt the telco business model will quite work out that way. I'm suspecting something more like $20/mo for voice-quality QoS and they'll never give up trying to keep me -- er, hackers, from abusing it and the call accounting system.

    Certainly the above ideas about paying for a higher QoS on a per-unit basis interest me, though! I'd love to see a wireless ISP (see what I did there?) try that.

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