Communications Error on Video iChat

Question

I am unable to connect with one son via Video iChat but able to connect with another son. I discussed this problem with the local Apple Store and they think it is an ISP problem. The one I am able to connect with; we both have Runner. The one with the connection problem, he has AT&T and I have Roadrunner; the Apple Store said I can try to " decrypt ", not sure what he meant. He also said I have to call AT&T to find out what port they use. Appreciate any help.

Answer 1

Hi,
There are two main problem ISPs in the States that do Data shaping in an effort to stop or control Peer-to-Peer file sharing.
They are Comcast and Road Runner.
The Peer-To-Peer stuff they are aiming at are the BitTorrent types where music and Video files are shared between many users at the same time.
However 1-1 Video contact and even 3 and 4 way Video chats are between those people only (Peer-to-Peer) and suffer the same fate.
The one way that seems to work best to get around this is to limit the speed at which iChat works.
iChat reads the System Preferences > Quicktime > Streaming setting.
In Tiger ichat 3 reads the Automatic setting as 0kbps
In Leopard it is read as 384k.
384 K is the minimum Upload speed at which iChat will do 4 way Video chats.
Setting the Quickitme Setting to 1.5kbps removes this cap at this point.
iChat needs to be restarted if it is Changed to "See" the new speed.
At this point the default Setting in iChat > Preferences > Video section > Bandwidth Limit drop down should still read NONE.
This is the Optimum setting for most people.
In the case of Comcast and Road Runner it seems that setting the Bandwidth Limit to 500kbps stops iChat being seen as "too grabby" of what Internet bandwidth you have. (i.e. iChat is now set to use a 1/3 of the internet Speed set in Quickitme and that is likely to be lower than your purchased service speed as well.)
iChat, if you have a paid for @mac.com name at both ends can Encrypt the chats.
It would appear that the "Guy" was suggesting that you use it in an Un-encrypted way.
AT&T were or are a telephone company.
Some Telcom companies have been worried about VoIP apps and devices making use of Internet connections to make long distance calls.
Apple declared iChat a VoIP app and use the SIP Protocols that are an International Standard.
(VoIP = Voice over Internet = IP Phones. SIP = Session Initiation Protocols used to Make VoIP connections).
iChat 3 does SIP on port 5060
VoIP devices and apps use SIP on port 5060 (or one of the SIP Ports (5060-5063) )
Some telecoms/ISPs block port 5060-5063 in an attempt to sell their Own VoIP service.
It is unclear from the AT&T pages I tries to look at about what they actually offer in Internet Service and Phone services as the first page you go to want to know where you live and I live outside their areas.
Also devices like Vonage Adaptors that are In line between computers and Modems can cause similar problems.
So the "guy" at the store may have been on about this issue.
Another issue is the way certain modems and routers do NAT.
NAT (Network Address Translation) has become an ubiquitous name for all methods of sharing a Public IP over a Private LAN
See here http://en.wikipedia.org/wiki/Networkaddresstranslation
This can mean that how your end does NAT and how your Son's end does NAT may not "play nicely" together.
If either of you is using Port Forwarding to open the ports for iChat and has UPnP that may help the situation.
Certain Buddy issues
Tell us what modems and routers are in use at each end and how they are set up to open ports.
9:38 PM Saturday; May 17, 2008