It is perfectly acceptable to use Skype, or other Voice over IP software over the ResNet. (Note that whilst Skype is described as using Peer to Peer protocols, it is not a Peer to Peer filesharing application and is not prohibited by the AUP).

However, some of the rules imposed by our network equipment to manage traffic on the network may interfere with the functioning of VoIP protocols, making it difficult to make phone calls to locations outside the network. If you are having difficulty using a particular voice application over the network, please let us know so that we can investigate it.