The iPhone & the Lack of Voice Over 3G: Alternative Theory

25 thoughts on “The iPhone & the Lack of Voice Over 3G: Alternative Theory”

  1. I’ve been running Skype over 3G on my iPhone(jailbroken of course) for the past several months and the call quality has been great to India. Not sure what their talking about when it comes to call quality degradation.

      1. You’re right, it is all about the network Om.

        I’ve done extensive development on VoIP over everything from 2G upwards. Some network operators (O2 for example) have very high throughput at certain APN’s and cell towers. With the right compression, and a very lean media protocol, even 2G voice can be at least “acceptable” and 2.5G (Edge) and 3G extremely good.

        Traffic shaping at the APN breaks real-time media, and many operators are employing traffic shaping.

        I’ve experienced fabulous audio quality over Edge and 3G using an O2 SIM, degrading to unusable (12 seconds of latency!) when switching to a Vodafone SIM but connected to exactly the same cell-tower.

        Operator data traffic shaping is typically done at the APN. This means the operators are in complete control over how good it will be (and to an extent they themselves may be limited by the quality/connectivity of the various cell sites to their POP).

        It’s hit and miss between differing cell towers, and differing networks.

        Something that the GSM operators can fix, should they chose to. It would likely require an investment in infrastructure however, especially with more remote cell sites.

        Dean

  2. I find all of the above very interesting. I use Skype to call landlines and other Skype users regularly on my Mac, using a standard 3G modem. The call quality is just fine and I have now completely dropped all office land lines and only have Skype-In numbers. Not only that, I use Skype on my iPhone using a shared Internet connection with my Mac via Airport to use IT’s 3G modem to make calls using the iPhone as a better handset.. All fine – excellent in most cases.

    Surely, it’s up to the market to determine the usability (or not) of a service? I don’t want to be “protected” from possible poor call quality by vendors, I’d rather work out if the service works OK for myself. Obviously, if it’s no good, the market will decide and it will die a natural death.

    I pay a capped rate for my phone calls so therefore if I “use up” my data allowance under my data plan, I will then start to pay extra for that data. Surely the carrier (Optus in Australia in my case) would WANT me to have a good way of using data so I get into their “sweet spot” of over allowance spending?

    Open up the market and let natural forces determine if VoIP on 3G will work or not.

  3. This is probably more an issue of AT&T not being ready for primetime, rather than making calls over 3G.

    All Canadian HSPA providers have sufficient capacity and performance to allow calling without issue – I make calls on Rogers HSPA network on a daily basis and have really never had an issue.

    My Bell Mobility MiFi 2372 (Canadian HSPA, not even the faster/less latent HSPA+ service available if you want it) yields ping times of about 50-60ms – more than fast enough for a serviceable VoIP calls.

  4. So At&T and Apple should start rejecting Apps that suck?

    Wow the App Store would go from 100k to about 46 Apps.

    I think the marketing guys might have a problem with that.

  5. I will join the others in calling BS on the explanation. Using HSPA in Canada and a jailbroken iPhone, I have been making skypeout calls for months. The only person who has been able to tell the difference is my mother when I call her mobile in India. The dead giveaway is the improved voice quality over the international call quality she has when she calls my Canadian cell.

    Other than taking away revenue from the LD charges, my suspicion is that the AT&T network is too overloaded to add in a bunch of us skyping away. I truly hate the fact that I can’t do skype without jailbreaking in Canada… we don’t have unlimited data, so really the carrier shouldn’t care how I use the bandwidth.

    –Dilip

  6. I use Skype while driving in Los Angeles with AT&T 3G on the iPhone some lose speech, but with Tilt 2 solid calls. If you have good reception it works great. 3G can’t support voip, not true at all.

    Man the iPhone has bad reception, don’t blame AT&T, try other cellphones before you post.

  7. it’s actually even more mundane than that…

    When cellular networks are transporting voice calls, they are using a much lower level, more optimized protocol than VOIP. They do away not just with the IP packet framing + a whole lot of other stuff that’s not necessary on the last mile link from cellphone to cell tower. The result is an Over the Air signal that requires ~4kbps per call.

    By contrast, running IP over a cellular network requires quite a bit more overhead and then when you run Skype over that, it’s akin to trying to run Skype over an old-fashioned dialup modem — there’s an awful lot of tech layers that gum up the works.

    Skype claiming hat they can run in 6kbps is sorta tough to believe but even if we assume it’s 40kbps, it means that a Skype call is 10x more bandwidth expensive than a “native” cellular voice call.

    On a broadband landline, the delta between 4 and 40kbps is lost in the margins but on a cellular network, it’s hard to ignore.

    1. Vinod, I work with VOIP quite a bit in my job, and G729 runs at 6.4kbps, and if your using silence detection you can make so that it effectively only needs more if two people are trying to talk over each other. Enhanced Full-rate GSM is like 12kbps. I understand there are issues with IP encapsulation overhead on a packet switched network, (and I hope someone replies explaining the overhead) but I feel that its more an issue of Data is given extremely low priority on the MPLS/QOS/Traffic shaping used. (http://tinyurl.com/yfxs7vc)

      High packet loss because the tower’s router’s buffer being full, or high jitter from it trying to hold onto too much too long (a misconfiguration in AT&T’s network that violates normal UDP throttling) is likely the reason why VOIP over 3G is unreliable.

      Lastly, there is an issue of battery life. IN order to use a non hardware accelerated codec (like G729) they are going to have to burn more CPU than a normal call and drain the battery quicker.

      BTW, anyone else having a giant dead zone in Houston on 290 between 610 and the beltway? Between that and the problems with tower hand-off if your driving in on I-10 I’m wanting to change carriers.

      OM, I’m interested in your thoughts if voice is becoming a race to the bottom, or an arms race in features? Old T1-PRI voice circuit’s i’ve had Tier 1 carriers admit that they only handle to get CLEC digging privileges easier for their fiber. The unregulated nature of VOIP has given it a interesting boom and i’m still not sure which way its going to go.

  8. Om, I live in the DFW area, ATT reception has been great for me especially 3G speeds. Everytime I call Mumbai specifically its been awesome to know the I can get a quick connection and call quality has been great.

  9. Om,

    Vo3G works if you are standing still and the cell sites your hitting have low traffic and you’re not being impacted by the totem pole affect. On the other hand I did a “Top Gear” style test in Austria on the Autobahn, breaking a few laws doing so.

    Cranked the Jaguar up to 220 K/h, made a 3G call and tried to talk..I was moving faster than the signal could keep up tower to tower on my Nokia E71.

    Game over….sure if you are in one place for the call it will work and sound “ok” but its a hobbyist’s play, not a consumer product offering just yet.

      1. Again, I think this is more a network issue than a VoIP issue. I travel throughout Germany quite often in the 200 to 260 range and have made VoIP calls. Yes, sometimes the quality is sketchy but for the most part it is pretty darn good. It would appear that the Finns and Germans have a pretty good idea how to build networks or at least manage the data part anyway. I have to completely disagree that VoIP is not ready for the consumer market. I am also realistic that no phone call is 100% error free, it is just that fixed-line calls heal themselves better. If I can do a Skype video call with my boss in DC while I am sitting in Finland using Sonera as the carrier, I am pretty confident 3G (based on the network) can handle VoIP calls.

  10. Skype over 3G is absolutely fine. I have been receiving Skype calls over 3g for sometime now and I am absolutely fine with the quality. It is just that the telecom companies fear Skype taking over the space completely.

  11. I’m all for VOIP on my cell, especially when it gets me cheaper international rates, but there will be two significant limitations: real life call quality, and 3G battery life. There are no phones on the market that deliver strong 3G battery life, it’s just a market reality.

    However, it should not be the carriers that make the call that these compromises are not worth accepting. The concerns around bandwidth availability are something the carriers need to learn to work around. The carriers have been upselling data plans for nearly a decade. It’s time they invested seriously in delivering the product they have been selling all this time.

  12. Om, I have to agree with the Canadians who have talked about the quality of the Rogers network.

    I know of someone developing an intelligent tethering product for BlackBerry (no details available yet). In fact the entrepreneur needs this product as he lives in a rural area near Toronto where there is no decent broadband cable or DSL availability but there is Rogers HSPA+ coverage. At home he uses his own product to “tether” to the Rogers HSPA and is making Skype calls (incuding video calls) as well as keeping up with his business activities over the Internet.

    While I cannot provide additional details at the moment I have had the product running on my PC over my BlackBerry Bold.

    As I have said many times after trips to the U.S., if you want to see how a 3G/HSPA+ network should work, move to Canada. (I am currently at IT Expo in Miami Beach and finding again AT&T coverage issues – thank heaven for WiFi access!)

  13. I have to agree with the people who use Skype daily to communicate via 3G. I have daily conference calls with my boss who is in the US while I am in Finland. I tether my phone (legally as the network operators here understand mobile data) and we use Skype with VIDEO to chat back and forth. Sorry but the Pat Phelan is wrong, wrong, wrong.

  14. Well I also disagree, when I was studying in the US last year, I was running fring on My Nokia N82 and it was perfectly fine, even for communications to France. I just had the T-Mobile unnlimited subscribtion for 10$ a month. I was based in San Diego FYI

  15. I think it is really interesting to see the difference in opinions about People based in the USA and in Europe for example.
    I’ve been making VOIP calls over Fring and Nimbuzz very well over locations in Spain, France and Scandinavia.
    It all depends on this. But nice article Om, thanks

This site uses Akismet to reduce spam. Learn how your comment data is processed.