Face Time: technology and implications?

Discussion in 'VOIP' started by Georg Schwarz, Jun 8, 2010.

  1. Yesterday Apple officially unveiled the iPhone 4, which comes with a
    video conferencing software named Face Time.
    It was stated that it only runs when connected to a WiFi hotspot.

    This brings me to some thoughts...

    apparently, unless Apple did some really wiered stuff, this is simply an
    all-IP video conferencing application, in principle much as there has
    been for maybe 15 years now. I assume, and please correct me if I'm
    wrong, that the audio signal also travels via IP. If so, this means that
    Apple themselves are now shipping a true VoIP application with their
    I'm wondering what protocols and infrastructure it uses for signalling,
    i.e. for call setup? What kind of addresses does the user "dial"? How do
    they identify their party to be called? Is Apple maybe running their own
    set of SIP servers to which iPhones 4 register? How do they deal with
    NAT and firewalls? I would be very much interested in the protocol
    details chosen. So far I've been looking on the web in vain.
    Irrespective of the precise details, if it really is an all-IP
    application, this means that communications goes past the telco operator
    (unless they happen to be the one contracted to run that service) - and
    so do the revenues (or rather there are no revenues any more).
    There might be technical reasons why Apple, for the time being, is
    restricting the usage to WiFi only (maybe they were short on time
    developing and testing, or maybe there were some QoS concerns and Apple
    did not want to jeopardize user experience). Technically speaking, at
    least with HDSPA, it is possible to have better network quality than
    many hotspots' uplinks, and any IP app could and does easily run in such
    an environment.
    So maybe the primary reason for restricting the usage to hotspots is to
    get some time to bargain with their partners, the mobile operators, the
    details of usage. Maybe they will use 3GPP video call standards when
    used on a 3G network, which would uphold the traditional telco revenue
    model. Or, even when using all IP, they could broker a deal with telcos
    that might mandate for users to get some extra 3G video calling option
    at an extra charge (much as they did some some operators with the
    so-called Thethering option) or get charged some tarrif when using video
    calling over IP over 3G. Since Apple is controlling it, that would be
    entirely feasable, and Apple could successfully negotiate their share of
    the pie.
    In any case, it looks like Apple is quietly entering the realm of the
    telco service prividers giving them ultimately the say about which
    services their users can use under which conditons and at which tariffs,
    just as traditional telcos do in the traditional telco business model
    (or as Skype does). This is yet another example where Apple apparently
    is about to change the rules of the game. Sure, technically speaking
    this is nothing new and has been around for at least a decade, but this
    is the first time that an influencial handset provider is shipping such
    a service ready to be easily used for the completely non-tech-savvy
    average user who simply wants to make a (video) call (if you ever set up
    VoIP e.g. on even a recent Nokia phone you will agree that this is
    cumbersome enough to deter most potential users, though technically it
    does work well - even over 3G, BTW).
    On the mid term, Apple customers will be demanding video call
    functionality wherever they are (i.e. not only in hotspots) as well as
    on/to other devices (I'm pretty sure the next release of the iPad will
    come with a built-in camera, as do already Apple's iMacs and MacBooks).
    Also they will demand and ultimately, when the service has more matured,
    get interconnectivity to other video chat services/devices.
    And unless Apple artificially does something about it, peple will
    discover this as a convenient cheap(er) way to have telephone
    conversations with their folks back home etc.
    So, my impression is that traditional mobile operastors who are still
    making most of their revenues on voice services have yet more reason to

    Any feedback to these thoughts would be appreciated.
    Also pointeres to the protocol details of Time Face would be very
    Georg Schwarz, Jun 8, 2010
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  2. For the time being. Eventually, it will run over wireless as well, maybe
    not until 4G is in place, but maybe over 3G. Regardless, it will be on a
    carrier by carrier basis, just as tethering is now.
    Because it is up to each wireless carrier as to whether they will support
    it; Jobs said that Apple is in negotiations with the carriers already.

    Here's about all that Apple has said about it to date:

    FaceTime works right out of the box ‹ no need to set up a special
    account or screen name. And using FaceTime is as easy as it gets.
    Let¹s say you want to start a video call with your best friend. Just
    find her entry in your Contacts and tap the FaceTime button. Or maybe
    you¹re already on a voice call with her and you want to switch to
    video. Just tap the FaceTime button on the Phone screen. Either way,
    an invitation pops up on her iPhone 4 screen asking if she wants to
    join you. When she accepts, the video call begins. It¹s all perfectly
    seamless. And it works in both portrait and landscape modes.

    I'm sure it works the same way if your best friend is male. <g>
    Michelle Steiner, Jun 8, 2010
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  3. This might offer some insight; it's copied from an article at

    The NAT problem

    For iChat AV to reliably connect with other clients (including compatible
    PC clients running the same complex suite of video chatting standards, such
    as AOL) across the Internet, it usually has to transverse NAT. That's
    particularly complex because everyone's NAT works a bit differently, and
    there's so many technical issues involved with handling different types of
    routers and their different implementations of NAT.

    There are different kinds of NAT, and no complete standards in place on how
    to implement them for ideal interoperability. Additionally, the security
    policy a company establishes for itself might rule out individuals from
    setting up their own server, which is a problem for video chat because
    iChat AV needs to act like a server for a remote client to initiate a
    transaction with it.

    Apple's iChat uses its own SNATMAP protocol to allow a client to determine
    its external IP address and open a port mapping that remote hosts can use
    to return communications through the firewall. Apple also uses UPnP
    (Universal Plug n Play) a Microsoft-originated standard for NAT port
    transversal supported by a variety of consumer router/firewall makers.

    These are used to punch iChat AV's traffic through NAT routers, but they
    aren't always supported by enterprise routers or some models of home router
    appliances. In Mac OS X Leopard, Apple improved things by adding support
    for ICE (Interactive Connectivity Establishment), an emerging IETF NAT
    transversal standard, but there are still vexing problems for non-technical
    consumers trying to set up a simple video chat.

    Making FaceTime open

    Apple faces the same kinds of problems in getting video calls to work on
    the iPhone. So do other vendors. Apple wants to make mobile video chat an
    open standard for interoperable video chat sessions, so it adopted the
    neutral FaceTime name rather than calling the service iChat, which is very
    much an Apple-sounding name.

    Essentially however, FaceTime is iChat AV for iPhone. Jobs presented an
    "alphabet soup" of technologies that were involved in making FaceTime work,
    many of which are shared with iChat AV, including:

    € H.264 and AAC, its ISO/MPEG video and audio codecs (just like iChat).
    € SIP (Session Initiation Protocol), the open IETF signaling protocol
    for VoIP used by iChat AV.
    € STUN (Session Traversal Utilities for NAT), an IETF standard for
    dealing with lots of different kinds of NAT.
    € TURN (Traversal Using Relay NAT), an IETF standard for allowing a
    client behind NAT to receive incoming requests like a server.
    € ICE (Interactive Connectivity Establishment) an IETF standard which
    helps set up connections through NAT firewalls.
    € RTP (Real-time Transport Protocol), an iETF standard for delivering
    media streams in VoIP.
    € SRTP (Secure RTP) an IETF standard designed to provide encryption,
    message authentication and integrity for the data streams.

    Rather than being some radically new protocol for video chat, Apple's
    FaceTime is an evolution of iChat's standards-based foundations, which have
    already been implemented by AOL in a compatible client on the desktop PC.
    It's therefore no stretch to think that other phone vendors will work to
    create compatible FaceTime clients that work with iPhone 4 phones, and it
    would be very surprising if Apple's own iChat AV wasn't adapted to work
    with the latest FaceTime protocols to enable desktop to mobile video calls
    at some point.

    The companies that need to buy into FaceTime are networking gear companies
    like Cisco (who already work to support the IETF protocols involved) and
    phone manufacturers like Nokia, RIM, HTC and Motorola (who are already
    working hard to match the iPhone's features, look, and specifications). The
    best way for Apple to push FaceTime would be to deliver an open source
    implementation of the core technology stack, much like it delivered WebKit,
    and much like BSD provided the world a standard IP networking stack.

    Apple understands the success of WebKit, but it's not yet clear that it's
    ready to give away software to competitors when it doesn't absolutely have
    to. That might result in a variety of implementations of
    FaceTime-compatible devices that all have various bugs that impede
    interoperability. Of course, such a situation might benefit Apple, too,
    making it the primary vendor of reliable FaceTime phones.

    Why FaceTime is WiFi only

    What FaceTime does on the iPhone is make video chat easy to initiate and
    use over the Internet, in high quality. In addition to running into the
    same problems with trying to get video chat to work across NAT boundaries,
    getting FaceTime to work on the less reliable, limited bandwidth of 3G
    mobile networks would be too high of a barrier, mainly because mobile
    networks are currently still vastly expensive to use.

    Existing video chat phones that work over 3G networks typically charge
    between .50 and a dollar per minute, which is not going to fly in mass
    adoption. Additionally, video calls are certainly not going to work on
    Apple's home state AT&T network, which is having enough difficulty placing
    phone calls.

    For now, the iPhone's new FaceTime feature is limited to WiFi, with the
    suggestion that this will change sometime after 2010 and the carriers warm
    up to the idea and dramatically enhance their coverage while lowering their

    However, most people who want to place video calls will be able to access
    WiFi at their home or office, making the limitation less of an issue. It's
    also interesting that Apple is pioneering video chat as a VoIP application
    rather than tethering the service to mobile carriers. That positions the
    iPhone (and the iPod touch) as potential devices to challenge the
    voice-centric nature of today's mobile networks. As next generation LTE
    mobile networks emerge, their IP-based connectivity will likely shift
    mobile networks from telephony to simply being wide area, broadband data

    Apple similarly pushed Internet email on the iPhone in preference to SMS
    and MMS mobile standards, which continue to charge archaic per message fees
    wildly out of proportion to the actual amount of data they deliver.

    What about Skype and Fring?

    The iPhone (and the Mac desktop) already support video calls via Skype.
    Apple even added support for Skype to run in the background on iOS 4 and
    enabled Skype to run over the 3G network in addition to WiFi. So why is
    Apple introducing its own Skype competitor, and one that doesn't work over

    For starters, Apple wanted a video calling app deeply integrated with
    iPhone 4 features, making full use of both cameras, being uncluttered and
    "one touch simple," and highly optimized to deliver great picture quality.
    It also wants to push open standards. Unlike iChat AV and FaceTime, Skype
    is not open standards-based. It uses an entirely closed, proprietary
    protocol owned by Skype.

    Officially sanctioned client apps that Skype approves for use on its
    network are closed source. Skype solves the NAT problem and addresses
    message encryption security in an entirely opaque way. It essentially does
    not trust the router and uses its own mechanisms for getting through the

    It claims to use an entirely decentralized system of connected users in a
    peer to peer network that shares the load between users, rather than being
    a point to point system like iChat, where a user calls another user to
    initiate a session. But none of this technology is open to peer review for
    security vetting nor openly implementable by others.

    That makes Apple's alternative to Skype, both on the desktop with iChat and
    on iPhone 4 with FaceTime, a strategy much like its positioning of open
    MP3/AAC audio against Microsoft's proprietary Windows Media Audio, or its
    support for H.264 over WMV, or its support for HTML5 over Adobe Flash for
    interactive content. In every case, Apple was working to build open
    interoperability over creating dependance upon a closed standard pushed by
    one vendor.

    Customers who don't understand this saw these strategies as "an attack" on
    Microsoft or Adobe or Skype, but these efforts actually work to open up
    markets and enabled Apple and other companies to both compete and

    The difference with Skype is that, unlike WMA/WMV or Flash, Apple isn't
    blocking Skype on iPhone 4 or the iOS. Skype isn't a direct competitor
    pushing its own hardware; Skype provides a product that addresses issues
    that FaceTime does not (support for earlier phones and 3G calls); and Skype
    is both already finished and functional and entrenched as a player in the
    mobile market.

    Other iPhone VoIP apps, such as Fring, support both Skype's proprietary
    protocol and can support alternative open network protocols such as SIP.
    That makes it likely that Fring or other companies could actually create
    multiple-network VoIP apps that support both Skype and the standards-based
    Michelle Steiner, Jun 9, 2010
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