iphone activation through a proxy

We had a problem today when a user did a software update at a school. When the update was completed we got error 9839.

I then connected the iphone to another mac and used internet tethering through a different iphone and the activation went through.

My guess is that the activation servers are blocked via the school proxy.

Does anyone know the location and ports that itunes uses for activation, so we can allow through the proxy?