25 Comments

Summary:

Apple & AT&T have come under criticism for not allowing VoIP over today’s 3G mobile broadband connections when using the iPhone. People are still asking why there is no VoIP over 3G. Some think AT&T and Apple are a conniving bunch, but there’s an alternative theory.

Apple and AT&T have come under continued criticism for not allowing VoIP over today’s 3G mobile broadband connections when using the iPhone. So much so that the matter got the attention of the FCC back in August, leading to explanations  from Apple and Ma Bell.

A few weeks ago, we had wondered why there were still no VoIP-over-3G connections. More recently, others asked that very question. FCC chairman Julius Genachowski sidestepped the issue during a conversation with Stacey and I earlier this month.

Now the popular consensus is that AT&T and Apple are a conniving bunch, and are preventing “VoIP over 3G” from taking root. But VoIP industry insiders have come up with an alternative theory — they believe that because the voice-over-3G experience is so bad, it makes sense for Apple, AT&T and others to not even bother with VoIP over 3G.

Our friend Andy Abramson has tried to make voice calls over 3G data connections via his jailbroken iPhone 3GS and has found the experience truly trying. “3G VoIP is not something I could consistently endorse as it’s not really ready for prime time,” he wrote on his blog.

Karl Good, Truphone’s director of applications, gives two reasons why his company has reservations about offering VoIP calling over 3G.

The first is that although a small number of networks, such as AT&T in the US, allow VoIP calling over 3G, this capability has not been approved by most operators, and has not been opened up across all handset manufacturers, such as the iPhone. As of today, iPhone applications that offer VoIP calling over 3G would not be approved by Apple for release into the App Store.

The second relates to quality. Although it is technically possible to offer VoIP calling over 3G on devices such as the Android, the relatively low bandwidth of 3G compared to Wi-Fi means that those calls are very often of a poor quality.

Pat Phelan, founder of Cubic Telecom, is of the same opinion and he offers an explanation as to why VoIP over 3G is a bad idea — at least for now:

  • Voice over 3G needs massive compression.
  • 3G speeds aren’t good enough for voice.
  • Latency, as measured by excessive ping times, makes it virtually impossible to have a decent conversation.

Skype in a recent filing with the FCC said it can run its voice service using small amounts of bandwidth — between 6 kbps and 40 kbps — so it doesn’t choke the network. But given the lack of latency on the network and other related issues, I bet even Skype doesn’t want to push hard to make its voice service work over 3G.

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  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. Monal

      My personal experience has been a bit mixed. Some days it works well somedays – well it is bad. I think it is about the network.

      Where are you based?

      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. Warwick Prince Tuesday, January 19, 2010

    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.

    1. That’s an interesting way of setting up your phones; will have to look into something like that.

  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.

    1. SP

      It seems your network is performing much better than AT&T’s network.

      What apps are you using and what device. Also, is your call quality consistent?

  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. Louis Cammarosano Tuesday, January 19, 2010

    VoIP over 3G Via Apple/At&T?
    They can’t even provide proper GSM telephony experience!

  10. 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. at 250k its even flakier
      watch out for those Austrian Police buddy :-)

      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.

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