iChat is a Mac Computer App only (Not an iOS app)
FaceTime is both but needs a WIfi connection fro the iPad.
Both iChat and FaceTime use ports above the 1024 threshold.
Most routing devices have ports below this figure open (Web Browsing on port 80 and if secure site, 443, whereas the mail app can use lots of ports depending on server but will be below 1024)
The easiest way to open ports is to use UPnP if the routing device has it.
Port Mapping Protocol does a similar job on Apple Base Stations/Time Capsules.
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
iMac 2.5Ghz 5i 2011 (Lion 10.7.2)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
"Limit the Logs to the Bits above Binary Images." No, Seriously