Voice over IP (VoIP)
ISS do NOT support VoIP on campus.
VoIP allows you to make telephone calls over the Internet. VoIP converts the voice signal from your telephone into a digital signal that travels over the internet then converts it back at the other end so you can speak to anyone with a regular phone number.
VoIP calls are cheaper than normal phone calls, though the service is not as reliable and you cannot call certain numbers such as the emergency services (999). Sound quality can also vary depending on the audio codecs being used and the available bandwidth. VoIP can be implemented in many ways as shown in the following diagram.
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A traditional phone network consists of analogue phones that talk to a PBX at the local exchange. These PBX switches are all connected over the Public Switched Telephone Network (PSTN). IP phones can be used on a PBX with the appropriate IP hardware.
VoIP can be implemented using software on your computer with a headset and microphone (softphones), adaptors used with regular analogue home phones, or phones designed to connect directly to the internet.
For VoIP to connect to the normal phone network it must use a VoIP gateway which could be part of the local PBX or a pay service you can subscribe to from a VoIP provider. For example Skype uses SkypeOut and SkypeIn to connect to the phone network.
Soft Phones
A Soft Phone is software for your computer that duplicates the function of a phone. Each service provider has their own softphone which you need to use on their network.
Although there are many fledgling VoIP providers appearing many are based on open standards such as the Session Initiation Protocol (SIP). The difference in service is the cost to access their VoIP Gateway onto the telephone network and other services such as voice mail.
Internet Phones
Softphones use speakers and a microphone plugged into your soundcard, this could be in the form of a simple headset. Internet phones provide another way of providing a sound interface by using a real handset that plugs into a USB port on your computer. Internet phones can also provide other functionality such as ringing when there are incoming calls and allowing you to dialout using the phone rather than the softphone on the computer.
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VoIP and the Campus Network
VoIP is NOT supported by ISS but that does not mean you cannot use it as long as it does not compromise services for other users. For example the Skype softphone acts as a supernode connecting to machines from off campus and generating a considerable amount of network traffic. If your computer is spotted running a supernode it will be blocked.
ISS do not block VoIP but we also have not opened any network ports to allow it either. There are a number of factors to be considered before ISS will support the use of VoIP on campus. Does it meet the acceptable use policy? Can the network cope with the additional bandwidth requirements? Also there are not a huge number of users demanding to use VoIP on campus at the moment but that may change.