

Wireshark: Facetime on Iphone 4: Vanilla unencrypted STUN and SIP - pmikal
http://blog.roychowdhury.org/2010/06/25/facetime-on-iphone-4-vanilla-unencrypted-stun-and-sip/

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jallmann
Hopefully once Apple "opens" up facetime, they will also enable calls outside
the Facetime network. Otherwise the who's and what's of connecting to their
registrar will probably be no better than the App Store situation today (eg,
I'm sure gateways will be forbidden).

edit: Although the identifying info from those screenshots is scrubbed, the
comments say the R-URI is basically user@ip:port. This is interesting: there's
no SIP proxy in between. No wonder it only works over wifi.

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andrewtj
_Although the identifying info from those screenshots is scrubbed, the
comments say the R-URI is basically user@ip:port. This is interesting: there's
no SIP proxy in between._

Unfortunately I see "Bandwidth Limit Exceeded" when I go to that page but your
comment makes me wonder whether they are doing SIP URI discovery via DNS-SD[1]
given their penchant for DNS-SD.

[1] <http://tools.ietf.org/html/draft-lee-sip-dns-sd-uri-03> (ignore the stuff
about mDNS and substitute Wide-area Bonjour)

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pat2man
Its actually a little more complicated than that:

[http://www.packetstan.com/2010/07/special-look-face-time-
par...](http://www.packetstan.com/2010/07/special-look-face-time-
part-3-call.html)

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michaelbuckbee
Since Facetime is running SIP over WiFi, does AT&T still charge you minutes
for a Facetime call or is that only for the non-facetime portion of the
phonecall?

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mattparcher
Apparently no:

“The voice call ends as soon as the FaceTime call connects... the FaceTime
call is over Wi-Fi so does not use carrier minutes.”

<http://news.cnet.com/8301-13579_3-20008289-37.html>

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yesbabyyes
This is cool. This, Google Voice and Sipdroid on my Desire (which lets you
route all calls, automatically, to the SIP provider of you choice, either on
Wi-Fi only or 3G as well) makes me feel good about the future of telephony.

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patrickaljord
Why is "unencrypted" considered a good thing? I find it kind of scary
especially for a video conference app.

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jallmann
Your phone calls aren't point-to-point encrypted, either.

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eli
No, not end-to-end, but they are encrypted between your phone and the cell
tower.

It's considerably more secure than an open wifi network.

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sp332
GSM supports optional encryption, but there's no notification to the user
whether a given call is encrypted.

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eli
Yes, but I'm pretty sure all US carriers use it all the time

(Though it's true that this opens you up to a potential MITM attack by a well
equipped adversary, it's still a far cry from an open wifi network)

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gsiener
Does anyone think they're trying to figure out IPv6 to make this work over 3G?

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wmf
What does one have to do with the other?

