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- Face Time: technology and implications?
- Georg Schwarz
June 8, 2010, 9:52 pm
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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
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
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 http://home.pages.de/~schwarz /
firstname.lastname@example.org +49 170 8768585
Re: Face Time: technology and implications?
email@example.com (Georg Schwarz) wrote:
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>
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Re: Face Time: technology and implications?
firstname.lastname@example.org (Georg Schwarz) wrote:
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
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
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
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
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