[Ti] is iChat different from Yahoo Messenger, MSN etc?

[Dennis Fazio]

On Mar 17, 2006, at 12:14 PM, Dr Trevor J. Hutley wrote:

> I was hoping that iChat would now work, with this DSL line.
> It works perfectly in Switzerland, but as soon as I get to KSA,  
> nothing.
> It has been like that for 2 years, so nothing to do with versions,  
> updates, etc.
>
> What is embarrasing now is that my friend, using his 17" block-of- 
> concrete laptop (Dell) is sitting by my router and happily using  
> MSN, Yahoo Messenger to chat with people all over the world.
>
> Does anyone know if iChat is configured in some way that could  
> explain why the software integrated in to the OS on a Mac does not  
> work yet 3rd party software in XP is just fine??

Hi, Trevor,

AOL instant messaging (AIM), which iChat uses, transmits on TCP ports  
5190, or also 5191, 5192, 5193
MSN chat uses port 1863
Yahoo messenger uses port 5050

It appears that a firewall somewhere is blocking port 5190, but 1863  
and 5050 are allowed through. I'd bet if your Dell colleague used  
AIM, he'd fail also. Since your iChat/AIM works in Switzerland, it's  
not your PowerBook. Either the firewall administrator has a bias  
against AOL, or nobody has come along yet to ask for access to AIM;  
just MSN and Yahoo.

Or perhaps the firewall administrator intends to block all chat but  
doesn't realize that MSN and Yahoo operate on different ports. If you  
inquire about opening up AIM and he says no, you may want to neglect  
to mention about MSN and Yahoo already working.
-- 
Dennis Fazio
dfz at mac.com